Sooo I get that if you drink a vialthey will give you whatever strain they're for, but does that mean when they re-open the volunteering program thing that's currently down, I can't get any of the other strains that ISN'T from a vial?

And how does this interact with the new wardrobe system where you can pick and choose your skins?

You can only progress one skin at a time, so if your vial isnt finished by the time VIP is operational, then you would have to wait until the vial finishes before you can get a VIP skin. Alternatively, if you don't want to wait, you could buy a cure for your vial through VIP and then ask for a new infection but I would not recommend doing that, because you would lose the progress on your vial.

Once you finish your vial, you will receive an event that says something like "Your infection has reached the final stage, so it's been converted to an avatar skin! You can now switch to the default human skin (or any other non-zombie skin you've unlocked) in the wardrobe if you'd like to get a different virus." You will be able to go to the wardrobe and clear your skin and then get another infection if you want.

Ah, perfect! Thank you, that's exactly the info I wanted :)