The c1 is good for hp numbers, but it has it's limits because of it's stock compression ratio of 10:1 and 10.5:1 if it's JDM.
Brakes and suspension all depnd on what you want to do.
Gsr brakes are an easy upgrade, front knuckles and spindles and rear trailing arms + the stock rotors and calipers, hoses and e-brake cables all from a 94+ gsr will give you full disc on the car, plus larger discs on the front over your stock setup. Then there is type R, you need knuckles, spindles, and rear triling arms with the rotors calipers, brake hoses and e-brake cables, this would be a step up from gsr in size, and will turn your car into 5 lug, which would mean you would need new wheels too.
There are powerslot upgrades too, as well as many other companies, it all depends on your budget.
Same thing with suspension, it all depends on your budget, I run KYB AGX adjustable struts with neuspeed 1.8" drop springs on my integra sedan with no problems, it's not as stiff as some suspension setups, but it only cost about 500-600 for the setup and the car rides real nice and looks good. make sure to add in camber kits front and rear and a toe kit for the rear so it is easy to adjust when you go for alignment. There are lots of different companies that offer wide ranges of kits, but with a car as light as yours I would stay away from coilovers even ground control because the spring rate would be too high for the weight of your car and it would ride like a brick.