To get to the upper shelf where the "fat kiddo that used to have a dog is" you need to pick the upper left exit on the previous map.
But there isn't much there.
I don't think there's anything you're missing. I could be wrong of course, spent less than 20 minutes on this version so take everything I write with a grain of salt.
For sex scenes... Nope, what the AI chooses is what you get. You can keep skipping turns and hope Saria gets it but there is no art for it in the current build far as I'm aware; only the bosses do. Also you have to remember that Saria can only get it on if she has high enough "corruption" on that specific body part... For which you're going to need to grind passives or your cap won't be high enough.
Although I should note that the latest update made each enemy have 1~3 bodyparts that they are interested in, so if there's something specific you want to see, make sure the enemy is targeting that bodypart. If he isn't, kill him and look for another one.
I think the starting choices impact what flavour starting gear you get. And, I'm going to hazard a wild guess that the last one will impact what Saria will most like doing because you get a "Fledgling X" crest on the equip tab that I presume is intended to grow somehow.
