Python 2, 88 86 80

Fairly straightforward, no bonus. Python is nice and lenient with global variables.

N=input();g=lambda n:n<1or(n%b<2)*g(n/b)for b in range(2,N+1): if g(N):print b

Best I've managed to get for the bonus is 118*.75 = 87.75:

N=input();g=lambda n:0**n*" "or" "*(n%b<2)and(g(n/b)+`n%b`)*(g(n/b)>'')for b in range(2,N+1): if g(N):print`b`+g(N)