I have a couple of general questions on a bathroom electrical layout (details are below)

I'm located in Massachusetts (NEC 2011). I have a couple of questions:

1) Can I run #3/7/8/16/4/5/14 all off a 20A circuit?
1a) Or should I split it to two 20A circuits, source to #3 and #16 (make it a GFCI)

2) I'd like to hide #16 and put it on the wall behind the toilet. I have about 12" between the wall and the toilet tank. The outlet's only purpose is for the towel warmer.
2a) I have plenty of room between the tub and exterior wall, but isn't that asking for trouble? The tub is a tub only, no shower though it has a hand wand.

3) I'd like the 15A circuit feeding #11/12 via switches #1/2 to tap off an existing 15A lighting only circuit in an adjacent hallway and bedroom (under 500sq feet of area). Does that pose a problem at all?

4) Last question I promise, anything glaring wrong with the layout?

LEGEND
#1 / #2 switches control #11/12 lights, 15A circuit
#3 GFCI fed with 20A circuit just for this bathroom, load side feeds/protects #7/8/4/5/14
#4 switch to control fan and waterproof shower lights
#5 ceiling fan only, no light
#6 towel warmer plugged into GFCI #16
#7 / #8 Medicine cabinets each have two 15A single outlets builtin
#9 / #10 dimmable flourescents
#11 / #12 incandescent fixtures above toilet and tub respective
#13 window on exterior wall
#14 two recessed waterproof lights for the shower
#15 dimmer to control #9/10
#16 GFCI protected 15A duplex just for #6 towel warmer