Experienced Developer, but new to Amiga

[Piru]

I'm really looking to get this working under Windows as I have a wonderful and comfortable development environment set up on my Win7 workstation through my CBM 8-bit work.  What would be great for me is getting VS 2010 working with the appropriate version of gcc and so any help in doing so would be greatly, greatly appreciated.

http://cross.zerohero.se/os3.html has a version for cygwin. As for setting it up with visual studio I have no idea.

[Piru]

Are there any tools available (for any platform) that can allow visual development of Intuition or MUI forms that spit out the appropriate C or C++ code?

Nothing really useful. The most common way is to iron out the GUIs by hand. It isn't that hard with MUI really.

If not, where's some really good documentation on the APIs for Intuition and MUI?

Intuition is documented in RKRM manuals, available from Amiga Developer CD 2.1 (available for example here).

MUI has pretty extensive documentation at http://www.sasg.com/mui/autodocs/

Be sure to check the various MUI examples as well.

http://library.morphzone.org/Magic_User_Interface_Programming has some nice introduction to MUI programming as well, although some of it falls into MUI4 category (which isn't available for m68k). Good read, regardless.