Odin, half GSD and half Boxer

His name is Odin. I got him from a breeder.

I think he is a GSD / Boxer mix.

His appetite is very good. He gets lots of exercise:
walk / run / fenced in big yard / dog parks

Odin is very smart. We got him when he was 6 weeks old and he is 12 weeks old now.

The only 2 challenges I have with him are:

1) Him peeing in he house. When I let him out for twenty minutes and see him pee, then he comes inside and five minutes later, he pees on the carpet?

2) His mixed breed - what is it called?