must have accessories for 2nd hand Z3??

Upgrading to a Sony Xperia z3 I bought on swappa, listed as mint condition but doesn't have accessories. (Coming from htc sensation & Samsung galaxy II- current). Should I use Sony brand accessories for charging, headphones and the like? I also need something to protect it from myself (just call me butter fingers) and onry terrorist toddler. I don't know anything about Qi or the magnetic cable charging technology or what to look for and steer away from. I need a case and screen protector I'm assuming? All the help I can get I would appreciate. Also, do you think I can/should pay for the monthly protection TMo offers? I really need this phone to last awhile.

Tia-
Cat lady