To answer your first question, I can’t think of a great way to filter a Choice component on a per user level. There is some discussion in this other thread that would possibly make it possible, but it is not a user friendly process and there would be a lot of overhead and gotchya’s that I haven’t thought of. I may experiment with this in the next week or so.
To answer your second question, I’m having trouble visualizing what exactly your asking, but if you are in a detail view and you use the Form Button to add a record to a sheet, you can include the column values from that detail view in the form submission.