CEL Codes P0171, P0420, P1259

Would love a sense check. CEL came on yesterday. Mechanic says the codes are:
P0171 Fuel System Too Lean
P0420 Catalyst System Efficiency Below Threshold
P1259 VTEC System Malfunction

> P0171 Fuel System Too Lean: Mechanic says I should be using a higher octane than Honda's recommended 87. 87 might have been fine when the car was new 12 years ago, but 89 or 91 would do me better, especially with gas formula changes over the past decade (does it make a difference that I'm in California?). At any rate, he believes my fuel system is dirty as a result of bad / low octane fuel, and I need a fuel system cleaning and fuel injection service.

> P0420 Catalyst System Efficiency Below Threshold: Bad cat. Need a new one. I suppose at 145,000 miles, this one has done its job.

> P1259 VTEC System Malfunction: Mechanic did not sound sure on this one. Reading the google-inter-webs (where all things are absolutely true and need no validation) looks like it could be solenoids or something as simple as the wrong oil viscosity. I intentionally use 5w-30 instead of the recommended 5w-20 because the higher viscosity means the engine drinks it slower. I already have to make sure I check the oil occasionally... and invariably have to add a 1/2 quart every month or two. Am I doing myself a dis-service here? Or is the VTEC solenoid more likely? Could this also be something as simple as a bad sensor?

Thoughts/advice/knowledge appreciated.