First wee in the morning - after being inside all night - urine will always have a stronger smell and colour - but during the day - then should be normal. I have found this to be the case with both entire and de-sexed males. So 'boy smell' - don't agree !
UTI ? With everything else you are saying - yeasty smell etc - vet visit is warranted and strongly suggested - with a urine sample taken in for testing.
Has the yeasty smell increased ? This could be a food related issue/reaction.
As Brian has only been with you a short period of time - there could be heaps of reasons for the smell. Was the smell very noticeable when he first came to your place - or has it changed dramatically since being with you ?
Change in diet - will also affect smell and colour of urine and stools - this would/could also account for the farts. Brian could also be reacting to the type of food he is now being fed. Some pups can have bad reactions to beef or any of the other meats.
Stress should also be considered and don't underestimate the effect it could have on Brian.
Good Luck and hope that you get to the 'bottom' of the problem ! smiley-eatdrink004.gif