1) Make it an active asteroid field, IIRC. You may have to add the ships to the escort list too.
2) There should be a SEXP to add escort ships. Look on
this list, it was generated using a newer build but the SEXP should be the same.
Squadron status, it has to be one of a few wings, although newer builds support wings other than Alpha, Beta, Delta etc.
Objective status, check the mission objectives dialog screen and the mission objectives SEXPs.
Don't be afraid to use VPView, QuickVP, VPMage, or VPCS2 to extract missions from a VP and see how people did things in them.
Also, look at karajorma's FAQ - the link is in his sig. I don't FRED much so I don't know if your specific questions are answered in there, but it's a good resource for mission creation/modding in general.