different centers seem to have different guidelines for patients post-tx, so i can only respond with what my tx doctor told me personally is response to similar questions i had:
1) the mask is not ever "required" (except maybe in clinics), but it is recommended in public, esp. around crowds
2) yes and no - my doctor said it was his job to "recommend" from a medical standpoint that post-tx patients not go into crowded places without a mask. he also said it was MY job to make my own decisions re the actual risks i was willing to take. he did say that the first year is definitely the most "crucial" for masks, etc, b/c that is when the drug doses are highest and risk of rejection is greatest
3) yes, my doctor said it is recommended that you not fly commercial airlines for about a year post-tx, but after that it's fine
4) this i KNOW varies from center to center. my center says no alcohol b/c it is generally bad for the body, can lead to infection, and b/c drugs post-tx (like prednisone) are processed in the liver. other centers say limited alcohol use is fine. i think the bottom line is alcohol isn't in and of itself a huge risk for post-tx patients, but like everything else mildly destructive to your body it isn't great either. it's really up to the patient to be smart.
hope that helps!