Figured I'd come out of lurk mode for a second to praise you.

Will, this is really good man! Vocal ability, 8. Authenticity in the cop, 7. You have to realize....if you don't sing often, it's not something you just pick right back up. It can take 2 days of doing a song before you come into your own...so don't be too hard on yourself.
Acceptance: This is the biggest problem we all have listening to our voices. Here's the deal with that. When you talk or sing normally without recording it, you hear the sound after it's vibrated through the bones in your face man. This is why when you hear yourself on an answering machine or a recording, it sounds like a totally different animal to you. When you hear it on tape or disc, the bone vibration coloration is no longer there. You cringe and say to yourself "for God sakes, is that really what I sound like?!"
Unfortunately, it is bro. But, we have never heard you like you hear you, know what I mean? So we'd be as shell-shocked as you if we talked to you often and heard your voice, and then some scientific tool came out that allowed us to hear what you hear in your voice, in your head. LOL!! So the key is to just accept it because you can't change it. It took me about 6 months to totally live with the sound of my voice once it was out of my head. As long as you're in key, have good dynamics, breathing and pitch control, it's a good thing.
I know you pride yourself on being a guitarist first and foremost, but that voice there is your gift bro. Seriously. A good voice goes a long way in music...especially if you can use it the right way and create something that may be acceptable by a wide array of people.
As for writing words etc, take a good look at some of the lyrics written today. I can't understand half of what they are talking about. Sure, there are some poetic genius types still around, but the object is to get your point across. Some guys tell it like it is, other feel the need to hide the true meaning of the song or give you double or triple meanings....there are no rules to me other than having a nice hook and a pleasant to listen to timbre.
Thankfully, you have more of a "good voice" than a "unique voice". I think the AIC comparissons would stop if you did it more often. It's like guitar bro. Sometimes we really latch onto a star and sound like them unintentionally....other times, we try our best to cop them. Sooner or later, we break out of that mold and find ourselves. But you have to keep at it and just do what you do without stressing out over what someone may think. That's the key there...your happiness. Do what you do...accomplish something, keep at it, and one day, you totally find yourself.
I've done a few cover tunes myself that I'll have to share with you sometime. Did a pretty cool version of Bryan Adams "Run to You" in a metal vibe. It came out so decent I sent away for licensing for it...fun little jam which sounds killer with a hard rock/metal vibe. I also recently did a cover of Daughtry's "Over You" which also came out pretty cool. Always loved the hook in that tune and just felt like doing it for the heck of it in my spare time. Covers are fun because sometimes we just need a release...sometimes we just need to do something that is fun instead of stressfull like writing your own stuff can be at times.
You did a great job on this Will...thanks for sharing. Would love to hear you do Man in a Box or Them Bones, Rooster or something...that new one Check my Brain is pretty bad ass too. That 1/4 step guitar thing is sooo annoying I find it cool due to the infectious hook that follows with that huge guitar sound. I know it ain't the original singer, but it sure is a catchy tune. Take care man...thanks again for sharing this.