A couple ideas I'd like to see implemented

I've been Planetary Annihilation Galactic War and I was thinking it'd be really cool if the factions had different units and not just different colors, or at least a different look. I know the commanders can be different but if they had some other unique units too that'd be cool I think.

I also think that adding some sort of force field thingy or shield to protect from orbital lasers and artillery would be great. I know the umbrella is great against orbital units but it does nothing against artillery.

Anyway just a few thoughts, Awesome game btw

I hate to be the one to say it, but pretty much everything you described is currently a 'no', sadly.

Id love to see another "race" of units too! Maybe even a human race. Though, tons will disagree and its not gonna show up in PA anytime soon. It would add a nice feel to the game.

This will answer your questions

http://planetaryannihilation.shoutwiki.com/wiki/Features:_Proposed_and_Confirmed

Two of your comments have already been addressed so I won't worry about them. Regarding artillery, sniperbots can take out at least some of it - I'm sure it can take out artillery from Shellers.

[edit] I might be thinking of when I tried out the Statera mod - try it for yourself

sniper bots can only shoot down the missiles from catapults and the t2 bot things

In Statera the bluehawk has the anti-missile role.

Nothing shoots down shells in any mod to the extent of my knowledge.

If you are searching after unique factions, continue searching after other RTSs then this one.
This one is trying to hold it balance by giving both sides the same ressources to use.