Xevra
Jambles-chan
Welcome fellow Whovian!
I agree, Tennant is amazing! Anyway, the first Doctor you saw was the 9th Doctor (black leather coat) and the 10th followed him (long brown coat and white/red converse shoes). There are 8 Doctors before the first one you saw. They are referred to as the "Classic Doctors" and the ones you are seeing now are considered "NuWho" Doctors.
Oh cool! That interesting.
Yes! When you finish the NuWho Doctors, maybe you could check out some of the other Doctors. Also if you didn't know, this is a really good 'skip around' series so if one Doctor doesn't catch your interest, it is easy to switch to another regeneration of him. All of the Doctor's regenerations have different personalities and appearances.