Looking to buy my friends 1995 speedster,

-Wondering what to look at when I get it, what to change etc.

-What are the most common problems and how can I prevent them, also he bought the boat 4 years ago, however any way to tell if the motors are going to crap? Or if they are original to the boat?

-Also being completely new to the world of jet boats, what do i need to know before going out on the water w. it the first time?

Thank you for any help!