Hey there,
There is no standard practice. Each group has it's own method and hopefully some will be explained here. The basic rule is do whatever is easiest to get it done.
My personal preference is (and I believe this is how Borealis does it - someone can correct me later) to have a binder with a whole bunch of copies of the waiver. Everyone - fighter or not, member or not - signs in & pays the fee if there is one. Then at reporting time the signed waivers are sent off. It's all kept in one place, no one has to chase down who's a member & who's not. This binder can also be used for demos where waivers are also required. Or there is a sign in sheet designed for the members to fill in just so we as a group know who attending practice and who's not.
http://antir.sca.org/Pubs/forms/27_Fighter_Practice.pdfThey sign it once and initial the space for each attendance. Non-members would still have to sign the regular waiver.
As for which waiver, yes, use the adult roster waiver.
We live in an age when unnecessary things are our only necessities.
- Oscar Wilde