Dude, if you're voice has been fucked for
two weeks you're either sick (which you didn't mention) or you've potentially really fucked your throat up. Blowing your voice out, even from bad screaming at a loud gig, shouldn't take more than a couple of days to recover from.
Getting tired after a couple of hours a day isn't unusual - singing takes a lot more effort than talking, and makes your vocals folds work much harder. Think of it like running; the more often you do it, the better your stamina will become. The key is to stop the
moment you start to feel like you're getting tired - a lot of people will go "right, one more take" and that's the one that does the real damage.
The other thing is not to force anything. That's the absolute killer - most people will strain and push to get grit in their vocals, and it just wrecks your throat. If you're recording yourself, it's easy to get stressed over repeated takes/bad tuning/etc. and that will make things worse - so you get more stressed, and so on. You
have to be completely relaxed - if you're getting annoyed with it, move on to something else.
"Singing with lots of projection" doesn't really mean anything. Better projection will come naturally with practise and technique - trying to force better projection will just mean you sing louder (which isn't the same thing), and you'll end up blowing your voice out even more quickly. Besides, people like the dude from Lamb of God and the guy from Chimaira actually scream just above speaking volume - certainly quieter than most people sing. You don't have to be Tom Jones to sound powerful.
If you think you will manage to do exercises regularly, go for it, but if there is a strong chance you will get bored... Well, my advice would be to make compilation of a few songs you like to sing and simply do them every day when you have some time. It doesn't have to be hard and you don't have to strain (get songs in your range!). Change songs if you like after while. Singing should be fun!
^That^ is spot on. Like any muscle group, control and tone (muscle tone, not musical tone) comes mainly from regular use - and doing endless vocal exercises gets really dull really quickly. All the exercises are doing is training up your vocals chords, it's just that they're more focused than plain singing. Make sure you have a couple of low ones and a couple of higher ones, but they should all be fairly easy to hit (if you want to try and extend your range, that's when proper training comes in).
Personally I think the Zen Of Screaming has the potential to fuck people up even more - it uses lots of terminology without ever properly explaining any of it, and it doesn't really cover any techniques in any depth - the discussion on "heat" (which every other vocal coach in the world calls 'vocal fry') basically involves her pretending to be Marge Simpson and repeating the phrase "above the pencil" until you want to use that very pencil to stab her in the eyes. The warmup exercises with it are good though.
Steve