minimap is normal sized i reckon. i don't have much use of it tbh. and making it smaller doesn't feel needed atm.
have in mind it's more of a draft what im posting usually. a lot of things are just idea's and things im trying out if i like or not.. im changing things
constantly 
nameplates i decided too try that look only too kind of match a theme or something. i didn't end up using that layout. because it looked cleaner without the panel around the name(s).
im fine with the overlay on bag's atm. does what i want atm. i sometimes turn off the overlay over the whole icon and sometimes don't . haven't decided yet what i prefer.
the castbar doesnt take that much space imo. and as a healer and endless different layout of castbar's this is the one that actullay brings me most attention in game.. it's very easy too spot when your target is casting even if you are focusing on raidframes for healing.
here are small comments on some elements..
http://img251.imageshack.us/f/blehwr.jpg/
not in a very sober state, so pardon my spelling etc. :P
hope that covers the questions asked.