Short answer: Yes, of course--to both of your questions.
Longer answer: There's seven rounds to go--that's 175 points still up for grabs. That's a lot of points left on the table. 44 points isn't that big a gap. 1 DNF from Stoner and a race win to Rossi at the same time would change the champoinship picture in a big way.
If Rossi won all seven races, and Stoner finished 2nd each time, Stoner would win the championship by 9 points. Of course, it won't work out like that, but it does show that Rossi doesn't have much margin for error. Any more mistakes on his part, or his team, or tyre issues resurfacing and then he will have to rely on Stoner crashing, or Ducati/Bridgsetone problems in order to bridge the gap (in other words, it hasn't quite reached that point yet).
The wildcards in this are guys like Melandri, Pedrosa, etc. They might take points/race wins away from Rossi (like Capirossi did last year). They could do the same to Stoner, of course, but at the moment the consequences are more serious for Rossi.
Several of the tracks coming up have been good to Ducati and/or Bridgestone in the past. But then, Stoner wasn't supposed to win at places like Donington or Laguna Seca, so who knows...
All of this means that Rossi just has to put his head down and go for as many wins as possible.