you really need to try several films and do your own testing.

as for the gear....

- 50mm Distagon lens.
good choice, i use the 40mm for extra wide, filters are a headache though

- 180mm Sonnar lens.
good lens but not sure why you need it

- Individual shades (I thought that the pro shade is too must hassle).
agree

- Spotmeter. Probably the Gossen Starlite.
i would go with a sekonic 608 personally so you can use it in studio etc in future

- A second A12 back.
agree

- PolaPlus back.
agree

- 16mm extension tube (for portraits with the 180).
too tight for portraits imho

- Lowepro Nature Trekker AW II.
good choice

will you be doing macro? why not buy the 120 mackro/planar, its great. good for portraits too.

a prism would be very useful also.