Hi,
We're very thankful for your generous review and many kind words, we're also thankful for raising concerns as it helps with unnoticed possible future QoL changes.
1. Relationship vs 'suspicious'
Those two aren't related, alas one depends in a way on the other - if you raise your relationship level high enough, you'll be able to give her "suspicious things" before the night starts. As for her being suspicious - if you leave mess before the night ends: cum stains, unclothed she will be suspicious of you and you'll have to wait few days for that status to clear (dev has plans to make it a visible flag, so that there won't be any confusion regarding it's status), while it's on you won't be able to participate in certain daylight events (only shower currently) and give her "suspicious things" before the night. That's all there is to relationship and suspicion.
2. As for this camera issue I'll ask dev once he's up and either I'll post the response here or hell reply directly.
3. Her clothes can only be manipulated while she's laying on her back, so if the night starts with her on her stomach, you take the blanket off, turn her around, undress her, then raise both arms up and turn her around again for doggy position after you raise her butt. Regarding the various explanation topic, dev plans to add a tutorial in some later patch, so it will eventually be explained, currently you'll have to play the adventurer and try various options and actions to see what is there to do.
Thanks again, hope my answers help.
Cheers