No - don’t do that. Cats generally don’t respond to “force” training. The best way to get them using their scratching posts is to play with them around them, like with wand toys or something, so they get their claws in them and scratching through play. Then praise them. They’ll get the idea.
Another thing, cats scratch not just for “claw maintenance”. They also scratch for exercise, and to mark territory. The marking comes in two ways: through sight (by the scratch marks), and by scent (cats have scent glands in the paws). Cats also do a large portion of their scratching after waking from a nap, so make sure there’s an appropriate scratching surface near where your kitty spends most of his time sleeping. Also, I’d suggest getting a few of those cardboard scratching boxes (Cosmic Kitty? I think is the name) - they are cheap (around $5/ea) and treated with catnip. You can toss one in every room.
For more information on cats and their scratching behaviour, check out this website:
www.catscratching.com
Don’t get plastic bowls - they tend to collect the oil from the food more than other surfaces and can lead to kitty chin acne. Ceramic or metal is the best.
Definitely get clumping litter! I can’t tell you how great an invention this stuff is. And I’ve learned that you really can’t skimp on litter. You’d think one clumping litter is as good as the next - not so. I tried to save money by getting the PetsMart brand of litter and it was horrible! I like the Arm & Hammer or the, I think, Tidy Cat Multi cat (or it might be fresh step, but I think not - I just switched on the recommendation of a friend).
Covered litter box = good! 
As for food, definitely follow violacrane’s advice and find out what he’s eating currently (maybe they’ll even give you a bit so you can switch) and feed him that at first. Any sudden changes in food can cause diarrhea. Start about 70/30 the first couple days, then 50/50 for a couple more, then 30/70 for a couple more and by the end of the first week he will have made the switch to what ever food you plan on feeding him for life.
At 7mos of age, he does not have to be on kitten food (unless he’s underweight). If you want my food recommendation, it’ll be a little more expensive, but it’s a higher quality food: Nutro Natural Choice (Indoor). You can get it at PetsMart and the reason I suggest that over something like Iams or Science Diet is that the Nutro doesn’t contain any By-Products, and after some of the research I did on what goes into pet food - that is a big plus. I believe that the Authority brand (PetsMart’s label) also does not contain any By-Products.
Ok… sorry about the above, I think I’ve spent way too long as an adoption counselor 