I am a devoted follower of the HPI bodies, In my opinon they have the cleanest sharpest designs over anything else.
They also have more selection than any other that I know of.

And yes any 200mm touring body will fit any 200mm touring car, its basically the standard. Just about all companies make the 200mm bodies in one shape or another.
The difference though is that you might have to cut the wheel wells a little different and the support holes different than what is shown on the body. HPI cars usually fit right into the pre marked cuts and so forth.
HPI bodies do also come with a protective coating that keeps overspray off the outside while you are painting.

Be careful in the hobby shop though, its easy to pick up a 190mm thinking its 200mm. The 190mm is for electric touring and so forth.

If you want to be roar legal for racing you will need a four door sedan type body. Alfa romeo and Dogde Stratus are very popular roar legal bodies. The startus is one of my favorites.

If you are into the 60's and 70's cars like the Camaro and so forth BOLINK makes 200mm touring bodies in various styles. Of course these are not roar legal but certainly look awesome.

Goodluck

Dbow