2001 toyota tacoma stereo

Hi. I just purchased this. It has a factory cd/cassette radio with seperate tweeter in doors. It is a extended cab. I want to use the factory head unit, but replace the speakers with mbquarts, and install a amp under the front seat. I have a older Sapphire As 1.0 that should do well until I can upgrade to a mbquart amp in the future. I also have a older bazoka sub that I want to use. The car is prewired with 8 guage wiring and ground, and remote wire. My questions.... can I use the factory head unit to power the rear speakers while my amp powers the front? if so how? What is the best way to wire the speakers ? Can I use the factory wiring... and if so what is the best way to tap into it? (can I use the existing harness or get a new one) How do i power the Sub and connect it to the radio? I want to do it this way first to save money and 2nd to keep people from trying to steal it. Anyone have the diagram for the 2001 toyota radio harness? I searched on the forums but could not find it. Thanks!

Many thanks for the quick reply, and link to that site. Looks like a lot to read up on. Can I use the stock head unit to power the rear speakers while the amp powers the front? If so do i just leave the rear speakers alone and cut the wires for the front... or is there a better way to do it. Is it possible to use the power of all 4 channels on the stock head unit to power the back, getting more juice out of it, or no? When wiring the bazooka sub, can I use the power off the 8 guage wire from the battery, or do I have to run a new power from the battery? I lost the original paperwork from the bazooka so I'm not sure how to run the wires for it. On the stock wires where does the remote wire hook up to? Thanks. All answers much apreaciated.