Average is 12-14 years although younger, relatively healthy people can go 20-30+ years. But in general, life expectancy is likely expected to be 20+ years lower than otherwise would be...unless modern medicine advances enough over that time to mitigate and/or nullify that which is entirely possible.
Not necessarily. That is obviously an immediate concern but it can happen at any time really and there are other potential chronic issues related to that always need to be on the lookout for.
Also, the immunosuppressives she will be on while needed for the transplant also increase risk for numerous other diseases and issues of other major organs like kidneys, liver, diabetes and routine infections which could become chronic and hard to get rid of.