There's many different polyester glazes available nowadays, Evercoat products get my vote Polyester Glazes
. Another option if you don't need a whole bunch of filling would be to use a polyester primer which is much easier to apply than skimming a whole panel with glaze. Polyester primers offer great build capability with no shrinkage. Polyester primers
If you apply two coats of epoxy primer over the clean and sanded bare metal before applying any polyester products the durability of the repair will very good. Urethane primer surfacers can be used over epoxy primers and polyester products as well. Southern Polyurethanes is a good source for quality epoxy and urethane primers as well as clearcoat.
A DA sander is a pnuematic sander that has D
ction capability, they operate as an orbital and also as a grinder (spin action). Some sanders these days are called a DA sander but actually only operate as an orbital making things confusing.