I've been using the Core for a while now and do love the little board. About your questions:
1) True, no nibs, but the keys are "deeper" or "rounder" (don't know how to describe best) so that you can feel those two.
2) You can move the Fn to the left side modifiers if you want.
3) True, but you can remap you most needed ones to a Fn layer, i.e. you only need to press Fn (no Shift)
4) Haven't tried that yet, but as I said, you can move Fn to the left side (including the left space bar) and use the arrow keys similar to the Pok3r. Or you can actually enable an arrow cluster on the bottom right corner.
If you get one, make sure to have the newer firmware on, before that Fn couldn't be moved and the both space bars acted as one.