Welcome the Technical Support section. Help us in assisting you by providing us with a concise and descriptive elaboration of your issues. Be specific and if possible, provide us with a step-by-step instruction in replicating your problem.
1) for import from frontend or jomsocial backend. It cannot, you must import it "manually" by using database manager/phpmyadmin direct to community_groups and community_groups_member tables. If you dont know how to do it, I can help you for this. first I need your cpanel/phpmyadmin access detail, and csv (zip compressed)
2) for group at register process it can't too much effort for this customization.
We have not received any response back from you in over 7 days, and would like to know if you consider this issue to be resolved. If you have any further questions, simply reply to this post.