@mdy
For me, testing to 1000BC doesn't necessarily mean planning to 1000BC, and that is especially true in this scenario. You're right, there are many unknowns for now. The testing serves at least these general purposes: 1) Gives us an idea of what this scenario is like and any traps to watch out for; 2) GIves us an idea of how many turns the various slingshots will take; 3) Gives us a feeling for the various MM possibilities we have, in advance, so that we're better prepared forthe various unknowns; 4) Hopefully helps us answer your question: where to settle, what to research, and what to build to put us in a strong position no matter what happens.
Traps to watch out for
1. DoPing Gandhi and the others. It turns out that this is a ROYAL PITA. We might play ourselves into a situation where we're fighting off a major SoD (=forget a medal). Furthermore, if we screw up the DoPs, the AIs will all max out their common war plusmods and those carry on through the game for all intents and purposes.
*** Without this testing, we'd have no idea about this. We're starting in an ALWAYS-WAR-type situation. No joking matter.
1.A. Did you know? If we don't get Gandhi to DoP before he meets Stalin, de Gaulle, and/or Mao, we may miss our chance to get him to trade with us in any foreseeable future, because we might remain his WE forever or until we give him a humongous tech. I didn't know this before testing, but now I do.
2. Fallout MM is complicated and unusual.
3. Both our development and tech pace are non-standard.
4. Gandhi starting with Alphabet is non-standard.
All of this takes getting used to. I don't see any way to learn this stuff other than testing.
Where to settle?
I'm anything but convinced that the coast is better than in place. The jury's out for me. Especially if we want to guarantee getting the AIs to DoP. Frankly, I'm not sure there's any good way to do that other than...beelining Alpha!?!?!

Have you found a better way?
REX
Again, not sure what we want to do, no matter what we find out down the road. Pure REX? REX+GLH? REX+Oracle? All three? Only GLH+Oracle, then REX? This is a very complicated start, imo.
In other words, your seemingly simple and wise prescription: "choose them so we will be in a strong position whatever happens"--I have no idea. Why do you think settling NNE, researching Fishing and building a worker will give us that? I'd be overjoyed if you could somehow simplify all this, because I'm struggling.
***EDIT: This may be worse than one might think at first glance. The various AIs can gain enough of these plusmods to be Pleased with people they have no business being pleased with. The obvious consequence would be that if we later decide to DoW someone, we get negmods with everyone else. As it is, if you check out the factors, it's currenty borderline for us to get any AI up to Friendly. Add 1 or 2 negmods and you can rule that out permanently. Do we want to do all the research alone?