If you have about $3-4K and a spare care you can have the motor built with forged internals, convert the car to OBD1 and use Hondata to tune. Slap a big ass turbo on the motor and push 600hp if you want to. If you have an automatic forget everything and just drive it daily until the transmission blows up soon.
If it's auto then the best performance mods you can do are a 5spd swap and suspension. Bolt ons do nothing on these cars. If the car is manual, then the only way to get signifcant power is to do what the guy above said.
Depends on what you use, where you get it from, and who does the work. Could be a few hundred to a few thousand.
Definitely could turbo the stock motor. No need for forged internals with a good tune and moderate boost.
If you can find a parts car for less than 500 with a good transmission you can just swap everything over