The OBD2 codes you get and those used by Volvo aren't the same #s and may not render the same wording to the user. Volvos codes are more specific and Volvo only gives out the necessary OBD2 info required by federal law in the US, even though Volvos diagnostics (Vadis in your case) is more specific.

With a 261a code, I'd agree: MAF sensor and they've become problematic in recent years.

As for the T-belt, 105K is the recommended interval and only once, reported at this site have I heard of one breaking prematurely. It's your car so if you want, there's no good reason why any dealer wouldn't replace it sooner if you request it as a preventative measure and your piece of mind. The fuel filter isn't required until 100K and I've never seen one clog, even on very old, very high mileage 200/700s where some were neglected.

If you've had all your services done, your brake fluid should have been flushed at the 60K service, look in your owners manual for all services advised.