So the Grand Unified, Settler level, Normal Speed, Optimal Strategy becomes:
1) Pop about six Settlers from Huts.
2) Move each one (including the original one) close to one of the eight AI Capitals.
3) Settle each of the seven Settlers on a PH next to PHF, so Hammer rate is 5 Hpt.
4) Build Warriors every three turns (Warrior = 15H = 3t x 5Hpt).
5) Attack each AI Capital when sufficient Warriors are mustered by its "sister" City.
6) Raze or keep each Capital as the economy can absorb the new Cities.
7) Keep remaining Civ on a very short leash.
8) Build Space Ship in the faster way possible.
Only serious ... er .... joking.
The real problem with winning at Settler level as early as possible is there are so many Winning combinations of Strategies and Tactics that it may be virtually impossible to filter them leaving the truly optimal Strategy and supporting Tactics at the Top of the Heap. From what I've seen on this thread, I doubt that any one is even close to the Optimal Strategy for this Gauntlet.
One bad assumption, and the supposedly "Optimal Strategy" ends up on the Scrap Heap of broken Strategies.
An Optimal Strategy would be much easier to devise, if Huts were banned.
Sun Tzu Wu
You are closer to the truth than you realize. The strategy you described is marathon speed in a nutshell w/no city razing. It doesn't work so well here. Step # 6 isn't necessary in BTS, only Warlords/Vanilla. (Yes, there are guys like me who have thought this deeply about settler level--a different gauntlet.)
Normal speed in a nutshell:
1. A modest but steady investment in exploration: build warrior/scout or scout/warrior. So long as you get 3 or 4 units from the first few huts it really doesn't matter what you get after that--cash is good to finance the exploratory phase. Just don't give up on exploration. A slight 4-5 turn delay in founding the capitol is worth it. It really isn't necessary at this level to have a contiguous empire
2. Research the two starting techs you don't begin with and target civil service not alphabet.
3. A modest level of AI aggression, have your war-making done by no later than 1800 BC. (This also works at marathon speed.)
4. On this map, sailing is worth more than iron working but you won't research it if you don't have to. Reason: see #3 above, notice the river nature and "Hey, there's no jungle around me.")
5. Settle a city or two around the capitol. Harness what you have.
6. Settle as many jungle cities as you deem necessary and get those workers out.
7. Step on the pedal and launch the ship.
The other points you made are interesting since I am contemplating Roosevelt and attempting a 1450 ADish win with him. Main reason: American leaders often get dismissed. Analysis: if he built everything Darius did he gets a production bonus one building (forge) and wonders plus a 20% kick on another. Downside: he's not financial and may need a corporate approach to compensate thereby losing some of his production advantage in the form of 7 banks and Wall Street. Still, I think he is seriously underrated for space games just not quite fast enough.
Edit: an optimum strategy is not possible at any level unless randomness is eliminated everywhere: huts, barbs, events, combat etc. I can say with 99% certainty that if you played the map I did you will acheive a better result (~2-5 turns) than I due to better luck across the board. And that's the problem. The very nature of the HoF is that you will be playing a different map. That is the single most random aspect that needs to be addressed. I am a pragmatist. I know that you will be playing a different map. I choose to play out maps that not only have zip but cater to poor luck as well. That is I expect you will have better luck than me, but is your map better than mine? Developing optimum strategy when different maps are being played out is impossible. Therefore I pay homage to the gods of pragmatism.