I study European Portuguese, and I'd like to discuss the following with you. If I have understood the situation correctly, there are three ways of addressing someone:
tu (the most informal, only between friends and family),
você (a little more formal, for someone you don't know of the same age (?)),
o senhor/a senhora (for elderly people, your boss, teacher, someone higher up in rank).
A few times I have heard the useage of first name + third person sing. verb as a way of saying "you". An example: Would you like some more wine, Roberto? --> O Roberto quer mais vinho?
But how formal is that way of addressing someone? Is it on the level of você? Or o senhor/a senhora? Would you say it to a friend?
Very grateful for you ideas here!
In European Portuguese, people use the third person form of the verb (in your example, quer) in formal situations as a sign of respect. The curious thing is that "você" is not used, because it's in fact considered disrespectful in Portugal, a reference to the fact that the person you are addressing might be older. I've heard that the younger generation sometimes uses it, but it's not considered acceptable my many. It's considered safest just to use the third person singular form of the verb, without anything else.
Saying "O Roberto/o senhor quer mais vino?" is formal. I use this style of phrase when addressing people who work in shops.