AMP and Battery/Alternator Question Recommendation

[Twrandall]

Hi Everyone, I've got a 2003 Air Nautique 216 (wish SAN 210) w/ PCM330 and its time to upgrade the Diamond Audio tower speakers and Alpine and Clarion amps. I've got a Clarion XMD3 head end unit. I've got a good line on a pair of Rev8s and Wetsounds HT4 and HT6. My thought is to run the HT4 bridged to the Rev8s and then use the HT6 for the 6 interior speakers (stock now but will upgrade in Spring) and factory 10" Polk Sub (picked up used on the boards). So for the HT6 I would bridge a pair of channels (300W) to the sub and run the 6 interior off the other 4 channels (one pair of speakers on two channels @110W and the other 2 sets of speaker pairs on two channels at 2ohms @150W or 75W per speaker). I may put in a WS420SQ into the mix too for the PA function. My objective is to have a clean sounding system that voice audios can be heard while boarding but not go deaf inside the boat (already hard of hearing according to the Mrs.). Boat has dual batteries (starting and deep cycle under observer seat) now with a 2 position perko switch.

Questions:
Would I notice the imbalance of the interior speakers power, 2@110W vs 4@75W each?
Should I keep the Alpine PDX 2.150 (300w bridged) for the sub and run all 6 interior speakers on the HT6?
If I keep the Alpine amp or add a third amp (thinking HT2 for sub @575W) will I need another battery or high output alternator for a 1500W or 2000W system?

I appreciate the help!

[MLA]

? 1) no, because you can gain down the pair receiving 110W to achieve balance.

? 2) excellent idea if space for 3 amps is not a problem.

? 3) The HT-2 is WAY too much for the Polk 10, so stay the course unless a sub upgrade is also in the works. You will not need a hi-output alternator. How many batteries or battery Ah's will depend on how long you intend to play the system with the engine off and not solely on the total watts.

[Twrandall]

So I broke down and picked up a WS420SQ which I will run to the HT4 (Rev8s), HT6 (interior) and Alpine (sub). This way it gives me greater flexibility and functionality and I don't have to remember the stupid setting on the XMD3 for the 2nd RCAs out to play full range. The PDX 2.150 is relatively small so we should be able to get it all in there. I've typically stored my fatsacs under the observer seat with towels and the pump so I will just move them to the bow under a seat. I figure we don't sit and play in one spot for more than an hour or two but I will probably need to add a third battery. Even then I can turn the sub and towers down so the draw isn't as much.