As far as freezing objects… if you mean locking them so that they are not selectable, then yes… open a “geometry window” and next to the object is a lock icon… toggle at you convenience. You can also assign a hotkey in the select menu.
The issue of auto-updating instances is not available in wings… you should complete your base geometry before extracting clothing.
The abs don’t look freakish, however a smoothed preview and character description would allow better basis for crit.
the 20kb limit is for CGtalk to host the image… i would bet that over 1000 images are linked to other hosts and 1500 images are attached a day in this community, limitations save diskspace and bandwidth, not to mention significantly reduce the time it takes to back it up each night… get a cheap host and host your own, then there is no limit or hassles.