Hey AE, I was the same. I was one of the first to own an EA copy very early on, then I followed for a couple of years, but for the past 4 left it all behind, however when I come to return I had forgotten my details, email account was now invalid and I couldn't remember what card I paid with so I just went ahead and purchased FPSCx9 again (how cool of me eh?) so people probably think I'm new but I have been around the full hog.
However, upon my return I see fantastic innovations not just in the engine but from modders and scripters alike. I will try answer as much as I can but only to my 'so far' limited knowledge, but as the engine is now much more adaptable, it is quite easy to say, nothing is impossible anymore. period.
1) Animated Textures ARE a go now, bond1 made a shader effect for this, which looks pretty cool however I haven't gotten round to checking that out yet.
http://www.youtube.com/watch?v=HwuJaR7016U
2) LipSync is certainly available too as DarkVoices was implemented, AFAIK it works with rigged entities, probably have to have certain bones again something I haven't got round to trying yet.
http://www.youtube.com/watch?v=Zo8fc7VMmYg
3) Out of all the mods developed, I have yet to see any talk of increasing map size. I think getting the current engine stable with the current map size is priority before expanding.
4) Culling has massively improved, even more with some of the mods such as WASP Mod. If you create simple portals, corridors etc. then it will render optimal frame rates from what I have tested. I have to admit, I have created 3 exceptionally large outdoor maps with plenty of static and dynamic entities and have managed to maintain optimum fps of at least 30 never below, however again, with the use of WASP mod using the same map I was achieving 50 fps!
5) The character/dynamic entity thing is still a bit of an issue, but most people are not adapting quite well to spawning enemies in a certain range/distance or when they are needed to save memory. However, I have noticed some frame rate drop with 3+ characters on screen at once, but nothing to complain about. It seems to worsen after 6.
6) I have noticed there seems to be reflection on the default water in the latest beta, however I haven't looked properly into that to see whether its hard rendered or shader rendered. I think one of the shader lads will be able to answer that one.
http://www.youtube.com/watch?v=BW1-KLD9kmY
7) Particle's are now in use for decals. Some videos on youtube (especially the Nuclear Explosion one) show some of the awesome effects that can be achieved. You can now also set the decal to remain static in it's position rather than turn with the screen.
http://www.youtube.com/watch?v=qeBcEnbC0w8
8) I haven't looked into making any models/importing into FPSC yet, but it seems this is possible. I downloaded a few of the free entities from the media section and a dynamic train I used I was able to freely walk in. Collision is still an issue, but not really with the player it seems to be more with the enemies.
9) I have been using the latest beta's since Jan and have compiled multiple test builds inc. SP and MP and haven't experienced a single crash yet.
10) Lots of notable improvements, probably too many to mention. I would go with the 'build on a whim' approach, in that if you start to develop your game using the latest beta, whenever you think you need something do a google search (forum.thegamecreators.com "search term") or use the forum search and no doubt you will have an answer or similar to what you are looking for.
FYI, the weather/night/day effect is now achievable using timers and a bit of scripting, however you would have to use a skybox without a sun (just clouds) as I don't think the skybox can be changed at runtime, so ambience and fog levels are changed to achieve the effect.
[Day/Night Cycle in the FPS Creator Community Guide]
also...
http://www.youtube.com/watch?v=i1yLHhnUhrA
Hope this helps dude, I am sure some of the more experienced shader guys/model creators will help you with the shader/model related questions a bit better.