I really think that right now your experience is MUCH harder than this process needs to be. Assuming that there is not some computer glitching going on, once you get things basically set up with your profiles, you will be able to get in a grove with this thing and it will really smooth out.
I don't know how many major variations of your listings you have, but just set up your BASIC item details, then your BASIC master profile(s), which is nothing more than a collection of specified item details. Once your profiles are set up you should not have to go back and make changes to a profile each time you do a listing. Just download an appropriate master profile (or individual item profiles) each time you create a listing, and THEN make minor changes on the listing page (the kind that change with each listing - price,shipping costs,etc.). Remember the item profiles and master profiles are just an AID so you don't need to keep manually entering repetitious data each time you do a listing - you don't even have to create and use them if you don't want to, although they really do save time. One very important rule I forgot to mention: NEVER leave a listing page that you are working on without saving it first! You will definitely lose your changes!
Once you have a BASIC set of SELLER details set up, you shouldn't have to be revising those constantly either.
As far as making changes to a listing that has already posted on ebay, yes, you can make ANY changes you want, subject to ebay's rules
I hope I'm addressing your issues. If not, let me know and I, or someone on this board, will be glad to lend advice.