Different tyre width (front and back) Out of necessity, I had to put an 1.26" (32mm) rear tyre on my bike where the front tyre is only 1.1" (28mm) wide (and the bike came with 1.1" tyres when I bought it). Are there any advantages or disadvantages of this, shall I try to get an 1.1" tyre for the rear wheel ASAP or is it safe this way?
Should be perfectly safe.  I actually did a similar thing on my road bike to allow a little more cushion in the rear, for my rear.  The only hassle I can see is if you have to carry two different tubes.  Can't remember off the top of my head if you can get some that span those two sizes.