i'm confused.....you have your uphill/downhill balance fairly dialed (if i read that correct), but you're having trouble getting on/off?  are you coming off the side of the rail?  what side do you normally come off on?
or are you just not popping off the end?  i didn't pop off the end for a while when i started sliding rails, you just need to get more comfy on them and the pop off will become more natural, especially if your slide is right at 90 for the whole rail.
as for trouble getting on, maybe you aren't popping and turning in the air?  or maybe you're like me and you're always sketched about hooking your back ski on the rail
-Strode
Abba Zabba, you my only friend