I'm 16 going to Spain?

I'm going to Spain for two weeks with my friends who are 16 and 17. Where is the best place for us to get where we can go shopping not cheap clothes but not very expensive. Also we all drink but we drink mostly like wine and martinis (our parents do allow us) and I hear Spain is lenient on their drinking age .... Will we be allowed to drink ? Also are we able to check into hotels ourselves if we book them online first or do we need someone over 18? if you could give me names of hotels that are lenient on age that would be great! Thanks!