Rat Pee and White Teeth

Question
I have two male rats that will be two months old late June. Recently, I noticed that their bottom teeth are yellow, but the top incisors are white. They eat, drink and play though. Are they okay?

So, number 2! When my rats pee, its an amber colored. It doesn't smell or anything. Is this normal?

Last question: Sometimes when I take them out for playtime, they have porphyrin surrounding their nose...

Please answer ASAP! There is an exotic in my area (vet) but they charge A LOT, so I don't wish to go until absolutely necessary.

I feed them a mix of Regal Rat, All Bran, fresh fruits and veggies, yogies, and the occasional milkbone for some protein. They are on towels and other fabric scraps, and otherwise have Yesterday's News in their litter pan and CareFresh sprinkled around for odor control. I clean their cage twice a week.

Answer
Yes, their teeth will yellow up with age. If they don't by the time they're around 6 months, then I would begin to worry a bit; but even so, it shouldn't be a HUGE cause for concern just yet. The darkness of urine usually indicates they're a tad dehydrated. Are they drinking enough? Do they always have fresh, clean water available? If so, the lack of odor tells me that it isn't a problem necessarily, and may just be normal for them.