@melen...please read the other thread on sensor dust...

1)You won't be able to see most of the dust on your sensor with the naked eye( the particles are far too small!).....so, the only way to find out is to do the test identified in the other thread.  The ordinary brush type blowers are not designed for sensor blowing....again, some makes have a powder residue inside the bulb as part of the manufacturing process....if you used that, it will blow all that powder right onto your sensor. The sensor blowers that people have found to be satisfactory are the Giotto's Rocket and Jessops (which I think is actually a Giotto's).

2)One of the problems using a blower is exactly what you've now done.....you can blow particles into the viewfinder screen...although annoying, the good news is that it won't show up on your images.

3)Don't know why you'd ever want to touch the mirror....both it and the viewfinder are quite delicate...again though, even if you've screwed it up, it won't show on your images....

I don't think you've done any damage to your Rebel, but if things are really annoying, you can always send it back to Canon for servicing

Sometimes, it's just best to leave things alone until they get intolerable....

In youth, we learn....with age, we understand.