You are asking some great questions, dude!! Let's get to work
#1 I hate your drum kit. If you brought that into my place, I'd say "Oh shit!". Then I would get stressed out because having that many round things makes getting the "big, resonant" sound without phasing real bitch!!!
I'm guessing you are doing the prog metal thing and it's totally common to use big drum kits for this type of music. Frankly, I don't have a clue how they record these big kits and still make them sound big and resonant (with close micing).
Basically, the bigger a drum kit gets, the less I look at it like a drum kit and the more I start looking at it like an orchestra piece. In other words, micing up every single tom would be a total disaster from a phasing standpoint without spending an enormous amount of time editing them. You do not have the tracks for this anyway, so that makes the decision to use less close tom micing easier.
The ONLY way recording a kit like this is going to sound anywhere close to not shitty is if you balance your kit EXTREMELY well. This requires a lot of skill / responsibility on your part and it all requires a room that will support this sort of sound.
In some rooms, an overhead mic will pick up a big thick tom sound even while it's picking up cymbals and such. In crappy rooms, the toms sound will be useless vomit shit in the overheads. I'm talking about the same mics, drum kit, and room. So choose your room wisely!
Your Room
It sounds like your room is pretty large. This is GREAT news! This doesn't mean it's perfect or even ideal, but based on dimensions along, it shouldn't be boxy sounding. (The worst thing a room can be, in my opinion).
Why do you insist on putting the drums in the center? Your room will have sweet spots. While I plan on making a video of this down the road, I'll try to explain it in text. Basically, grab a middle tom or floor tom and walk around the room. REALLY listen to how the tom sounds. Listen to the fullness of the low end. It will change. Make a note of it and walk around the room with the snare drum. See if the natural ambience of the room works with it in the same position. The center may be the best place, but don't decide that with your brain. Decide with your ears and studio monitors.
Ambience
I would not use a single blanket at first. I would find the sweet spot and really listen to the drums. You can get away with a little room sound in the drums. I love live sounding drums, personally. This is up to you, the band, and the style of music. Slowly add blankets as you see fit. Stop when you are happy.
Engineering
You didn't mention the style of music and this is EXTREMELY important for the engineering thing. Assuming we are going for the usual multimic'd drum sound, I'd try to keep everything super simple. I WOULD NOT sacrifice the overall fidelity of the kit just to get some big boom out of the toms. This big boom thing is HIGHLY over rated anyway.
I would take my time getting the core sound at first. For your big kit, I'd start with just kick, snare top, and overheads. Work very hard on just this and don't use any other mics for a long time. Really work on the placement of the overheads. These need to pick up everything. You may consider putting the floor tom side overhead about 2' out from the floor tome and maybe 1' above the flloor tom. Basically, I'm suggesting that you can control the amount of cymbals in your overheads by placing them closer to the stuff you want more of. So "sort of" mic your floor tom and see where that gets you. Remember, it's still picking up the entire kit, though.
I'd measure from the snare drum with a mic cable make sure the other overhead microphone is the same distance from the center of the snare top as the mic that we put close to your floor tom. You need to be careful because you annoying hihat is over on this side. Usually, with this mic I'll put it 6' or higher into the air and point it down at the snare drum. The mic may end up over the crash cymbals, it may end up coming from the drummer's left shoulder. Who knows! Experiment.
Using these two mics will help you get the resonance you want out of your toms, still get a nice picture of the overal kit in stereo and should keep the fidelity of the kit high.
I'd have no problem using a single kick drum mic in this situation. Don't complicate things with phase cancellation especially when you only have 6 tracks. If you had 20 tracks, I'd say to go ahead and put a mic inside and a mic outside. You don't. No BIG loss, really.
Room Mic
Next, I'd add the room mic. Spend a lot of time on the room mic. Really listen and try weird ideas. Try it 6 feet from the drum kit. Try it 20 feet from the kit. Try it in the corner of the room. Try it everywhere. Try it loud in the mix. Try it soft in the mix. Whatever. There is only one way you can really screw up a room mic (besides a crappy room and poor positioning) and that is picking up an excessive amount of high end. I'd rather be crucified than use an AT4033 for a room mic. The cymbals will tear your skull apart. I don't know what your other options are, but that would be the last mic I would choose. I'd go for something dark for the room mic.
Toms
These toms will not be robo huge and powerful, but if your playing, the room, and the mic position supports it, you will get tasteful toms with lots of tone. If you are used to close mics, you will not be super happy with the way the toms are "tucked" in the mix more than likely. They probably won't jump out unless you play that way. If you have a midi in, I'd highly recommend using triggers on the toms and triggering them with samples. If that isn't your bag or you can't swing it, I understand. There was a time when I let personal pride get in the way of the quality of my records, too.
With only one mic left, the options are slim. 6 channels is slim pickings for a kit like this. One option would be to listen to the room mic and see what it is adding. If it is adding something awesome, great! It HAS to stay. This depends entirely on your room. If it's not adding much, scrap it. I have a new idea. Go ahead and mic each tom and pan them. Do your submixing, but keep them in stereo. Toms don't cut through well when panned center. Spend a lot of time making sure the levels are the same on the toms. Don't look at meters. That's useless. Instead, use your ears. If a tom is quiet, it's quiet. Turn it up. You'll want to hit the damn toms VERY hard, more than likely.
I'd spend some time on the tom submix. I'd mute all the tracks and see what happens. You will get some bleed in there. Actually, you will have A LOT of bleed in there. Don't worry about that much from the recording side of things. The bleed is the fault of the drummer mostly. If you hit the toms robo hard, the bleed will be drastically reduced. If you play like a pussy, the toms will be useless. Serously. The ball is pretty much in your court to make this work. The best engineer in the world would probably tell you the same thing.
Snare Bottom
Hmmm. We are out of mics. I really like the snare bottom, too. I guess your shit out of luck on that one. In that case, make sure you get plenty of crack out of your snare top mic. If it sounds dull when solo'd then it will probably screw up this whole recording. I'd back the snare off a little more more than usual. The proximity effect on a 57 is a killer and we need the snare to crack a lot in this case. I have a feeling that if I mic'd this kit, we'd end up with a 57 about 3" from the snare. Who knows what angle and all that crap. I'd have to be there for that.
I hope this helps.
Brandon