Wanting to upgrade car audio system, How?

lot of tech stuff building computers scratch or opening computers , fixing them. fix minor car mechanical problems , simple head unit/stereo installations , wiring. totally have no idea car audio amplifiers , subwoofers.

first of all, current system:

pioneer deh-6300ub head unit
4 x 50w mosfet amplifier 2 2v rca preamp outputs system expansion

http://www.amazon.com/gp/product/b004clyog4/ref=oh_details_o08_s00_i00

sony xplod xs-r1344 5-1/4" 4-way speakers (front)
impedance: 4 ohms
power handling capacity: 160w

sony xplod xs-r6944 6" x 9" 4-way speakers (rear)
impedance: 4 ohms
power handling capacity: 300w

sound wouldn't great @ higher volumes. aim absolute best quality sound system. play cool jazz/pop/rnb/techno stuff , don't play @ loud volumes want best sound quality.

i'd understand how correct way of matching amplifers, subwoofers, & speakers

1. need replace hu or speakers? bad?

2. l need subwoofer aside amplifier?

3. speakers 300w , 160w each speaker? or 150w , 80w each? 4 speakers 2x150w , 2x80w?

4. know these peak power if 300w+160w = mean need amplifier more 460w?

5. speakers use 4 ohms can 4 ohms amps? using 2 ohms amp bad?

6. if need subwoofer need separate amp or connect 4 speakers+subwoofer on 1 amp possible? if so, wattage range should for?

7. speakers need amp? , should subwoofer dedicated amp?

i'm sorry have lot of questions i'm confused @_@ please help!
(at least, don't need post 7 questions separately :d)

i lot of tech stuff building computers scratch or opening computers , fixing them. fix minor car mechanical problems , simple head unit/stereo installations , wiring. totally have no idea car audio amplifiers , subwoofers. first of all, current system: pioneer...

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