I would say the M2 Pro edges out the M1 Max primarily because of its better GPU cores. It’s just that the difference doesn’t feel all that great when you factor in getting more RAM and storage for the Mini, which bumps the cost up into the baseline Studio range currently. But the M2 Pro is hardly a slouch, so if you’re on a really tight budget, focus on the best CPU you can get for the Mini and as much RAM as you can afford to put in. RAM more than anything else is going to determine how quickly the machine becomes obsolete with how Apple’s unified memory scheme works.
I would expect it to be loud. It’s a SFF type enclosure, so not exactly much room for a large fan nor is there a lot of room in there period. Once you factor in having to use Macs Fan Control for a better fan curve, noise could become an issue. Such is the price to pay to keep these little buggers cool enough to avoid thermal throttling.
That’ll depend on both your MFC fan curve setup and the settings you use in WoW. Follow Omegal’s advice and you should be able to eke the most out of your Mini with least amount of drawbacks.
It does need to be said that as with all of Apple’s M-Series offerings, get as much as you can into your machine when you order it because everything is soldered to the motherboard and cannot be upgraded later. Be aware that unless you have a really huge budget for scads of built in SSD storage, you’ll need to add a TB3/4 external SSD/NVMe drive at some point in the future. The default amount of SSD storage is pitiful by virtually any standard.