Hi! I am a member of Online Kappa. I can speak to our procedures, but every online chapter is different. Some operate just like a land chapter with meetings, programs, and socials. Others are more like a chat group or e-mail list. You should "visit" a few to see where you find the best fit.
Also, it is important to know that some online chapters will take brand new pledges, and some will not. You'll need to check that out.
I don't know which chapters are most active. I hope you find a chapter that works well for you.
Erica