As for the windmill: I think you've meant
not on a hill.
As far as the rest goes:
Pioneer - stats good, buildings are good, but library's missing - I know it's gamey, but it's one of the main issues settling after some time is not feasible, and after some more time not even remotely viable. Also walls - I don't really think walls are a good idea - Barracks maybe, but walls? We're almost past the times of walls - some people might build them, yes, but I don't think they are suitable, though quite historically accurate as a "fortification" - but starting a castle day 1 in a new city might be a bit crazy (since we don't have an intermediate defensive building such as a watchtower or pallisade - walls take a lot of time to build and can't actually be brought by the new settlers (unlike most other buildings, which can be assembled at the site). Barracks, as "place where your city guard stays and where you train the military
if you train them", make much more sense here instead of the next level - especially that it's by theme also a defensive building, to train people who will protect the settlers from hostile natives (why are natives always hostile? And why are we "defending" by taking their land and burning their villages
).
I'd remember about conquistadors, the Spanish UU, not the historic ones
- I know they receive little love, but allowing them to pop at least on this level is something that should not be forgotten (we fought for that in RoM times, don't even know why, since I never played Spain in civ - but it just made sense, and it makes sense now).
Colonist - stats good, would reduce population to 5, but maybe that's me (6 is a bit too much and perhaps too heavy on happiness - easy to starve a 6 on unimproved tiles without being a shoshone - easy to starve 5 as well, but not as likely). Windmill is great, but might be unbalanced - well, it might also be great, depending on how much they will cost. The rest is excellent. I don't know if it's possible to leave Pioneers as an option when Colonists happen without the AI going crazy like it did in RoM, but it might be worth considering, since even a pop5 city might not always be the best idea (especially that it must require
a lot of production for all those buildings). It's better to give more buildings and increase the cost than make cuts, since that wouldn't really solve many issues. Giving the Colonist a bit of leeway on the culture borders side of things, a very minor shoshone-like effect would be in order to provide the city with workable tiles. On this level, I don't think shoshone will feel bad about this (their ability would still be better, and it's not like it matters that much after initial landgrab).
I cannot express how awesome this is, but I will try: it's truly awesome to the point of teenage-groupie mass-scream of joy ;p Yup, that awesome. I just can't describe with words how many things that might fix.