correct about the DB being 4 doors. the 7 and 8 after means wat kind of engine it has. the DB7 has the b18b1 non-vtec engine, and the DB8 has b18c vtec (also known as the GSR engine).
as far as the salvaged title goes, have a mechanic look at it before you buy it, some places do it for free, some may not. I am lucky enough to have my dad's best friend be a mechanic so he took a look at it for me at no charge. I have heard that the trunks in integras tend to have a leaking problem, other than that, just make sure all the body panels fit together straight, the engine has no ticks, etc. other members on here may have more to say about that though..
good luck with the hunt!