My celica was sitting next to the ocean for almost 2 years.
there is a lot of salt deposit and corrosion type of deal going on under the hood. and in several other places.
.. i was wondering if anyone knows of the best way to remove some of it without taking everything out and sanding it off etc..

For the salt, soap and hot water.

For the rust, heh, take your pick, there's loads of ways to remove it.

However, long term, your car is probably junk.
The salt spray will have gotten into everything most likely, once you start rusting in the seams and wiring harnesses the car is usually destined for a slow death.

How much you want to do depends on how far you want to go, and how much money you want to spend.