Walk Behind Lawn Mowers

I havde a Husqvarna hu700f thats about two months old. I had been having no problems until this inicident. I was cutting the backyard and went over a tree stump. The mower immediately cut off and the blade was bent pretty severely. I went to lowes and got a "universal" blade but I dont really have a good feeling about it. Also, when I resumed cutting the self propel was barely pulling at all. I turned the mower back over and saw that the belt had slipped from the pulley. I got it back on turned it over and restarted it. When I pulled the lever nothing happened the self propel seems to be out completely. I guess I have two questions. One is can you advise me as to where I can get a Husqvarna blade and what is the part number I should be looking for(either online or locally). The other question I have is what should I do about the self propel in order to determine what is wrong with it so I can fix it or have someone else fix it.