Hey Monica!
Temps are usually whatever you are comfortable with. If acclimated, birds can live in below freezing conditions.... most people on the forum tend to keep temps between 68* to 80*.... however my birds are mostly used to temps that are low 50's to high 80's.
If you are worried about him being cold you can get a ceramic heat lamp, heating pad, heating panel, some may even recommend heated perches.
As for Ryan, well I'm afraid I'm not sure what you could do, other than trying to show him that it can be fun interacting with Casper (but not pushing him to interact with Casper in any way). In time he may become more confident.