Replying to Switching up on rails?

Got a quick question, since I want to learn these this year...

First...easiest type of rail to learn these on? I am very comfortable on rails, switch ons, reverse 270's out, etc, etc...but what type of rail is ideal for these switch ups on rails? F-D? Straight rails? Length? Anything...?

Second...now I know I am most comfortable sliding left foot forward on any rails...have yet to try left foot forward (should I try before doing switch-ups?). But which way do you start a rail knowing your going to switch-up...do you start your natural way, then pop the 180 and slide the rest your un-natural way? Or is it vice-versa?

Thanks, hope to see some discussion... :)