need help door speakers

[naughtyca]

current equipment

amp Rockford PBR 300x4 75watts @4ohm x4

http://www.amazon.com/Rockford-Fosgate-PBR300X4-4-Channel-Amplifier/dp/B004T163SY/ref=sr_1_1?s=electronics&ie=UTF8&qid=1360326108&sr=1-1&keywords=pbr300x4

Cadence FX8M4 4ohm 8" $125watt rms front doors

http://www.amazon.com/Cadence-Fx8m4-8-Inch-Mid-bass-Speaker/dp/B003TN8MQ4

I want to use my current equipment for mids and highs

I'm thinking

getting 2 more Cadence FX8M4 4ohm 8" for the rear door

getting 4 tweeters

http://www.onlinecarstereo.com/CarAudio/p_25156_Cadence_XT20.aspx

or

http://www.onlinecarstereo.com/CarAudio/p_33501_Cadence_CVLT45.aspx

will this set up work and how am i going to wire this, I am thinking i wil need to get another amp

I also found some 2 ohm 3.5 which are 2 ohm, can i use this and still use the current factory amp? my factory amp is still installed and powering all tweeters right now

http://www.onlinecarstereo.com/CarAudio/p_19642_Infinity_Kappa_329cf.aspx

here's the layout of my car its a Mazda cx-9