You can lose the main merc and continue. You don't even need to do the test. At least if I remember correctly. I think we should just hire all the MERC people, they are cheap and can fill slots, particularly militia training. But we can wait until we take a town and a mine.
Ok, I'll rank my recommendations:
1. Wolf - solid all around
2. Trevor - Good lockpick and repair, decent soldier
3. Thor - Good backup medic and solid soldier
4. Sydney - need a sniper, and he reminds me of Walsingham!
5. Barry - good explosives, backup repair, can be a good soldier if he doesn't blow up
6. Some doctor, Spider or MD I guess. MD can get pretty decent if given a lot of training
7. Ice - Chill
8. Hitman - Hitman once killed 18 enemies on a single map for me...in JA1.
Forgot we need an ox - Grizzly causes less problems then Steroid. If we get Danny, no Steroid.