I do not have plans to continue updating the walkthrough, no. If I do, I'll probably start from scratch and do it a different way, such as just recording relationship score adjustments from decisions and then what score you need for gatekept branches. I'm generally pretty good about answering questions over on discord, though, if you have any.
As for the second question... Generally, sleeping with someone won't block off a lot of options, but there are a couple exceptions. I will probably redo the earliest scene with Nick at some point as the decision tree for that was a bit arbitrary and was when I was just starting, but the idea there was more that if you had made decisions more aligned with a pro-Mayhew mindset, then you wouldn't be able to sleep with Nick. I haven't done a lot of that since, but... There is and will be a series of optional encounters that, if pursued, will block off certain endings. There are hints about that, though.