Emma 100% has big dtf bisexual swinger energy. Perry is probably gonna keep fiddling his thumbs for at least a few more chapters even if you give him maximum support, so I expect Emma to be more sexually active in Lena's side of the story even if Ian ain't encouraging her on his.
As for long term guesses, getting Perry and Emma together will have complications at some point with the whole Perry trying stay apolitical due to his relationship with his dad and Emma being much more engaged. I think some lesbian action between Emma and Lena could happen after their show, and maybe that could lead to Ian and Lena having their first threesome, who knows. Even if Perry and Emma get together, it is possible his porn addiction may have given him a bit of a voyeur (and potentially cuckhold) fetish, and with how kinky the both of them are, I think it is possible they could invite Ian or Ian and Lena for group sex at some point (with Perry maybe standing a bit on the sidelines or not).