You can try throwing some parts at it and you may very well fix it but it is a crap shoot without the proper tools to diagnose it. You say you got a great deal on the car, is the previous owner on the hook for any of this stuff. In California a smog is required on a transfer of ownership and the selling party is responsible for both providing it and any necessary repairs to get it through the inspection. Do you have any emissions warranty left, 5/50 on emissions and as much as 7/70 on certain high end emissions components and that is federal not state to state. Barring all that stuff if you have no other route I would spend the money and have a Volvo dealership or a very well equipped independent diagnose it and repair it properly. The VVT (variable valve timing) solenoid is probably a pretty good guess on the VVT codes. IF it is not a leaky gas cap on the evap code then it could be a number of things all of which are pretty tough to diagnose without either a smoke machine and/or Vadis, preferably both.

Good luck, Mark