Also - What is Vcc in this circuit - is it 5V?
Yes, it is. The resistors were chosen from fitting standard series values to expressions for amplification (m) and offset (b) while minimizing MSE for (m,b). It turns out that for these particular parameters of feedback loop for 3.3V output both input divider and op amp output divider are about the same order.
// case #1.1.1 ($4.3.2): non-inverting amplifier with negative shift
// Vout=m*Vin+b, m>1, b<0
// m = (Rf+Rg+R1||R2)/(Rg+R1||R2)
// |b| = Vref*(R2/(R1+R2))*(Rf/(Rg+R1||R2))
All four resistors values in this configuration are heavily interlocked, I can't help it if they are the same order of magnitude for certain conditions.
p.s. here in the code comment I'm referring to 'OP AMPS FOR EVERYONE' by Bruce Carter and Ron Mancine (ISBN 978-1-85617-505-0).