The 0 (zero) key on your num pad should do a RAM preview.
Is there any way to get it to start from the playhead rather than the start of the range? I already have my preview set to play from "Current Time."
Assuming that you're using After Effects CC 2015 then not with the default settings, you'll have to fiddle with the options available in the Preview Panel to get it to behave how you want it to. It's now a lot more customisable that what it was in previous versions.
Hope that helps
Thanks again! This really helped me.