"Are the engines really fragile?"
Not as fragile as balsa but more fragile than a brick, you could smash it beyond repair on the first crash or it could survive 100 crashes.

"I am only planing on using the plane for about 1 year then i want to upgrade to a different plane."

you may use it 1 year but then it could be 1 month or 3 years it depends on how you feel, guys i know that have been at it foe 20 years still bring out the trainer ocasionaly.