general questions on unit/amp/speakers

Hello, I am new to car audio and am building a system for my 86 4runner. I have purchased the following till now, but am not sure if it is the right combination. It will be great if you can give me some suggestions. 1. Alpine CDA-7897 head unit ( bought from ebay, doesnot work, hoping to get it fixed from alpine certified service center) 2. Front speakers are MB Quart D CC108. they are small like 3 to 3.5 in speaker, I have posted another question on this. 3. Boston Acoustics RM6 speakers for rear. The manual says max music power 200W, peak input power 100W and continuous input power 50 watts. (these values are for each speaker right?) Actually when I bought these speakers, I was not sure abt their power rating and I dont know if I shd connect these directly or through amps (below) 4. Kenwood KAC 648S 4/3/2 amp. which says 280 power max. and another MTX 275X amp 5. Rockford Fosgate 8 inch subs (2) The reason I bought 2 small subs and not one bigger one is that I dont want to use up the cargo area and would like all speakers/subs hidden in the sides. I am planning to connect the rear speakers (boston RM6) and subs through the Kenwood amp and connect the front directly from the head unit.. Is this a good combination? Should I use another amp for the subs? Any other suggestions? Its OK if I have to buy any other amp. then I ll sell this/these amp(s) to get money for new amps. Thanks!

It sounds fine to me. Wire one sub to each of the channels on the MTX 275x and the four coaxials to the kenwood KAC-648s (make sure to use the high pass filter on the small dash speakers especially).

I was checking the ratings (RMS) on the speakers, HU and amps and found that the alpine head unit gives 20W rms per channel and the kenwood KAC-648s gives 25W rms per channel when hooked to 4 channels (4ohms) So it seems there wont be much difference if I hook the speakers through this amp. When used as 2 channel, it will give 70W rms (4ohm) but my speakers spec (Boston RM6) are 50W rms only so I guess I cannot do that. Should I go for some other amp? Or I can do something so that I get more wattage (than 25W rms) from the Kenwood KAC-648s and still not damage anything. Any suggestions?