As I've been yapping about before in other threads, give AmiDevCpp a try. It runs on Windows and lets you build Amiga executables. Run the executables in WinUAE to see how they work, then test them on the real thing afterwards.
For transferring files, you can either:
- Use crossdos and mount 720k MSDOS-formatted disks
- Get a PCMCIA Compact Flash adapter
- Get a PCMCIA network card
I have all of the above on my A600 just to be sure.