I would say the average austrian family celebrates a simple christmas. On the 24th (mostly at the evening) you will sing carols while standing next to the christmas tree, after that everyone gets their presents. Most christians go to church very late at night like 10pm or even 12pm depending on the location.
The following days it will continue as long as the family wants. Some visit their relatives for days some only celebrate for 2 days really depends on the family.
hope I could help, merry christmas