OK, first about the Donahoes. The coilovers are adjustable. You can control how much actual lift you get out of them. I set mine for 2" of lift in the front. The harder you crank them out, the stiffer the ride will become. When I combined the C/O's with the Deaver 10 pack rear springs, it leveled the truck. Total I have about 1.5" of lift over stock in the rear, and 2" in the front.
I chose to add Total Chaos upper control arms so that I could align the front end easier. If you don't, it will make aligning the front more difficult, that is if you have the C/O's cranked out too far. The farther you lift the vehicle, the farther it moves out of alignment and the more you need to bring it back in. The uniball upper control arms allow you more flexibility when you align the front. They also allow the suspension to cycle smoother and get that extra bit of travel out of the extended travel Donahoe's. Remember that every time you adjust the ride height, you will be putting the truck out of alignment.
If you want to keep your stock wheel, you have two options. Run the narrower tire, or add wheel spacers. The spacers move the stress point outward. Its not really a problem if you buy a quality set, but I wouldn't trust the sets from pep-boys and the like. Just make sure that they are torqued down properly and it should be OK. Wheels are preferable because it allows you to move the tire outward without adding another stress point. There's arguements on both sides, but as long as you're not planning on beating the living piss out of your truck, you should be OK. You could keep it stock with the wider tires, but there will be some rubbage at full lock, and you may get rubbing on the UCA's with the tires you're planning to run.
The 255/85's allow you to run a 33" tire without having to change anything. If it was me and I didn't want to drop the money that would be the route to go. You may not get to run the brand of tire you want (selection in that size is limited) but you cant have your cake and eat it too. I think the BFG's and Super Swampers are the only M/T's you can get in that size.
It's definitely a more expensive setup, but I've helped a couple of people switch out and I always hear the same thing. I wish I would have done this in the first place.
As far as pricing for the Donahoe's, check out Wheeler's offroad for package deals.
http://www.wheelersoffroad.com/05updonahoetacoma.htm
The Donahoe's with UCA's are running $1,375.00 Thats only $285 more for Camburg UCA's. Thats freight and tax included (no tax ever in Oregon)
Demello offers a package with the deaver rear springs, bilstein shocks and Donahoe C/O's for $1650.00 If you want to add UCA's its only $439 more.
http://www.demello-offroad.com//catalog/product_info.php?cPath=27_25_30&products_id=98&osCsid=132d9ce54a9a52f5d2654eaddd3d8d19 Thats a pretty darn good deal. Tell them you're from TTORA and see what they can do for you. Jason's a heck of a gnome, err I mean guy.
Hope that helped,
Chris