What you have is pretty good, and will serve you for most situations. What is really important in dealing with first aid situations is knowledge and skills, most particularly the ability to do a decent survey of the victim and extract a decent history. With the exception then of a few items that really should be sterile (and even that can be improvised) everything else depends upon your ingenuity and improvisational ability. coupled with your judicious selection of some multiuse items.

I do feel I would rather use medical tape than duct tape since the adhesive on duct tape is almost too good, but I don't think people are dying from the use of duct tape.....

I think you are right on in putting everything in a sandwich size ziploc, unless you are out for a very long time and very isolated.