itch.io

between around 6 and 10 pm on a school night (aka when you couldn't run into the RMP)

No Good Gourdtember does interfere a little with the sexy times with the BFF, but as soon as the month is over, you should be good to pick it straight up again,

Don't know if you're talking 3 in-game days or 3 RL days, but I'll try to answer keeping that in mind.
I've found it pretty reliable that your date will invite you back to their place after a dinner date. How much they're willing to do depends on how well they know you unless you turn off dating sim progression, but both of you should get off by the end.
The only way to get threesomes pretty regularly is to become polyamorous, or at least have an open relationship, and invite two or more of your partners to "hang out" somewhere as part of a date. They should all degrade into a sex pile after things get going.

No, I'm talking about Viridian Forest to Pewter City. I managed to buy the map for it a couple times, moved to it, and had no way to go backwards.

I found it very easy to move to the second zone and then get trapped there with no way to go back. You should at least be able to return to the starting zone without having to reset the game!