Do we have enough spots left for everyone? 
depends on who it is. this is why you assess needs, look at the numbers, and match them up with the prospects. that is why posts such as the one saying "I'd sign all of these quarterbacks and, derp, it would be a good idear"....is not a good idear.
'Hatter, is the idea of "counting back" something that can be used this year, and if so, what is it? I count 4 grayshirts from last year, leaving 21 spots for this year.
27 but more than likely two of those spots will go to Akinola and Clement. Yes, there are 4 greys: Small, Seiwert, Jones, and Vaughn.
27-6 = 21.
We have 9 current commits though I think it's possible someone like LeAndrew Gordon is a grey.
21-8 (9) = 13 (or 12)
needs:
QB (2): Ertz
RB (0)
FB/H-Back (0)
WR (3): Vaughn and Jones
TE (1): Small
OL (4 or 5): Clement, Allen, and Seiwert
DT (4): Akinola
DE (4): Willis and Wood
LB (4 or 5): Williams
Secondary (5 or 6): Green, Jackson, and Moore.