Rafiki,
first of all you should send this as an email to Rainy, i´m sure he will appreciate that.

but i doubt he visits this message board.
for your questions: Rainminder is not a standalone program, but a LiteStep module. it can do everything you asked for, but needs LiteStep running as shell or on top of explorer. have a look at the Rainminder and Rainlendar documentation at Rainy´s site for more info. a "Rain desktop" would not make sense as all of Rainy´s programs are LiteStep modules (2 of them also as standalone EXE), so there is already a "Rain desktop":
LiteStep