1. I personally am fine with any position.
2. Assuming Asterion is fine with it, then some thinly veiled promises, less SFW PDA, etc.
3. Refer to answer 2.
4. Sauna, a hot spring, things like that. Also, while not R&D, it would be interesting to create a new, binding contract that forces both to abide by a safe word and requires both parties to consent before sex.
5. I feel Asterion might be alright with certain public displays (see answers below), but draw the line at full on public sex, so if the room has no lock, no sex. Personally, I'd enjoy some optional watersports content, but am unsure how he would feel about it. Potential threesomes seem like they're a no-go. BDSM is off the table, but leather might still be appealing to him.
6. A few public ass grabs or a foot on his bulge below the dining area table.
7. Trapping the MC against a wall for some flirting/teasing, some quick gropes during a hug. For some scenes, I'd enjoy the option for a dominant bottom Asterion.
8. I feel Asterion might have developed a slight praise kink, maybe a breeding kink, musk seems likely. He'd love more soft, tender lovemaking mixed in with some of the kinkier stuff, in my opinion.