XX,
I think your list is pretty good, with the possible exception of the St Ives Lancers - call me grog, but they're not a Capellan Capellan unit ;) How about Syn's Hussars - from FM:CC, "Dark green trimmed in jade green or appropriate 3-color camouflage trimmed in jade green" Go the three-colour camo base.
Also, use the hex base edges to denote faction. Capellans jade, Feddies mustard, Leaguers purple, Combine red, Steiner Ultramarine blue ;) Don't use bright versions of the colours, it'll distract from the basing & mini.
And I'd go Lyran Guard over Royal Guard - they're the backbone, and the Royal Guard can be a little ostentatious ... Yep, I know they're meant to be!
General comments - white is a pain to do until you find your zen path to whiteness. Having done a whole Level III for WOB, I dont' want to hurry back there. Greens, browns, and reds lend themselves easily and well to inks and stains, which produce tabletop quality with less effort. For example, you could do Davion Deneb Light Cavalry - base with tan, cover with teak stain, and detail - bang!