For scenery, I wouldn't go importing any from other flight sims. CFS2 has been out long enough and there is tons, and I mean tons of scenery to download that was created for CFS2. Stick with that for now. I would suggest that you get ALL of Mask Rider's scenery. It covers just about the whole of South East Asia and is the best looking stuff out there. Get it over at http://www.sim-outhouse.com It's in the scenery section. Several downloads of various geographical areas.

As far as acft. go, you are fairly safe with FS2k acft. and many of the FS2k2. I wouldn't try putting FS2k4 acft. into CFS2 as they are different in gauge set up and can cause conflicts. Download and install ONE ACFT. at a time and test it. Then if there is a problem, remove it.

Also, for a much, much better look to CFS2, I suggest you get the Pac Tex Texture Mesh download. It is large but has been broken down into small packages. But well worth the trouble. Get it here:  http://myweb.tiscali.co.uk/brigstock/CFS.htm

Those two scenery downloads I mentioned above, IMHO, are a must have for CFS2.  Have fun!!