One theory running around on the aging thing is that he aged because he didn't have the TARDIS around him.
In terms of the Time Lords giving him another regeneration, I thought that it was another "regeneration cycle"... what struck me at the end was that the new Doctor didn't seem to remember...
I've actually read that each of the five titles will be unique and have something to do with the story they precede. Last night's definitely fits that model.
BBC Canada (in Canada obviously) was showing the older series, and showed series 3 about 6 months (or so) after it aired in the UK. At least we get that DVD set in January. Maybe we'll luck into seeing series 4 over here by the end of 2011. Heh.
Aside: Next week's episode pair features...