So the romance/erotic scenes are more a reward for completing missions? That's completely ok, many commercial games go this way.
1) Sounds like a good concept. The "hunters and collectors" principle is always fun. You can also make a connection between the dungeons and the romance scenes. For example, you do not only find better gear, but also clothing / toys /... that can be used or even trigger the romance scenes.
2) Does not sound that exciting for me. Might work, but it could feel like you are playing two different games that have no real connection to each other. The goal is survive game 1 long enough to see the good stuff in game 2.