Audio needs

I'm hoping to improve audio for my 09 pre-runner. I'm looking at a after-market pioneer head unit (AVH-X3700BHS) and it's capable of a rear view backup camera.

Any of you installed a pioneer head unit, how difficult is it to install?

I'm also liking the super crew dual sub box to put two 10's in it, so any suggestions on which subs are best but not extraordinary expensive?

Lastly, do I need to get new door and rear speakers along with the head unit and subs or will the head unit would supplement and the subs would give more power?

Thanks

 

Well, I've only installed like 2 radios and I installed that same radio in my buddies taco. However I didn't hookup the camera or the sirius or anything like that, just the microphone for the bluetooth and the usb cord extension. pretty simple install from my experience, but then again, I didnt do the camera.
(i have very limited audio equipment experience)