I'm running an Ultimachine RAMPS v1.4 on a MakerGear Mendel Prusa.
My laptop runs Windows 7, with Python 2.7.2 installed.
My usual workflow is
(favourite text editor) -> OpenSCAD 2011-10-5 -> Slic3R 0.5.4 -> Pronterface -> Marlin 0.9.10L
I'm happy! Marlin is smoother and quieter than Sprinter, and does curves better. You need Marlin nonGen6 for RAMPS, the V1 fork doesn't work on RAMPS.
Slic3R is faster and easier to set up than skeinforge. I sometimes use skeinforge43 for parts that have very thin sections, since Slic3r seems to optimise out bits that are only one strand thick. See my post where I talk about the raven cookie cutter. I may just need to tweak a setting somewhere, but haven't felt the need yet.
3. The perfboard is already cut at 45 degrees angle with the edge, and just fits the size of the platform V 2.0. When printing starts, plastic will have more chance to be pushed into all perforations, and this provides a stronger mechanical bond with the bottom surface that prevents it from later lifting.