I'd vote no RC (let's see how it plays with majors this time) and no SS (less minors means less potential to snowball?). But I'm on the fence with the latter.
I'll test to try to be sure, but my understanding is that SS adds more zones w/o adding more population. That'd mean that there's more non-minor zones (nomads, slavers, mutants, etc.) but also the minor regimes would have lower population per zone simply b/c there's by necessity more zones to account for.
I'm also kinda wary b/c one of my hotseat tests had 3 zones per major but apparently the engine couldn't find a spot for one where it could have 3 and gave it 1 instead. I submitted a bug report for that, FWIW. No response as yet. That's the main sort of reasoning I'm using to lean towards 2 instead of 3; it seems like the engine is struggling for room sometimes and that's even before we consider if it can space things out.
Re: critters, it's a crapshoot. The save you requested from me with the rhinos killed me the first time I tried it but the second time I was fine b/c I started with different specific wildlife next to me. I'm honestly more scared of something midsized with a nasty combo of feats than a giant beastie, b/c I'm not sure I've ever seen more than 1 attack on something over 40m, while something 15m with 8 or 16 attacks per round can vaporize battalions in a round or two.
I suppose it's good to pay attention so that you have things like heavy/high-tech industry discovered and built at some point before you actually need to use those.
At a certain moment it might be wise to stop researching new techs until you discover Heavy or High-Tech Industries. I'd say that's most true with Heavy. I ended up doing that with my econ council for several turns last game, but you may need to do it with mil and air as well if the alternative is opening a new tier and potentially indefinitely delaying your getting Heavy Industry.
[Edit: Hmm. I'm growing increasingly convinced that SS is indeed leading to more population rather than just spreading what there is more thinly. Drat.]