Someone please help with Bose system!

I have an 06 altima se 3.5 with the cheezy factory radio and ndss speakers. All i wanted to do was setup an aux input so I could use my ipod...i bought the converter and I needed to buy the bose head with the 6 disc changer because the original head wouldn't work with the converter i bought for the ipod. so...i installed the bose head and converter and everything works but the output is really low for the radio/cd and ipod. after a little research, i now realize i need an amp and bose speakers to go with it. here is my question (bear with me i know nothing about this stuff)...

will it be easier for me to get a bose factory amp, factory bose speakers and have the car re-wired for all of this OR can i buy an after-market amp with some sort of converter (i know the bose amps typically operate at 1 ohm instead of 4) and leave the speakers i have and upgrade them later with non-bose speakers?

also I'm assuming that since currently the wires run from the head directly to the speakers, that i'll need to have everything re-wired in either scenario above to go from the head, to the amp and out to the speakers from there is this correct?

I want to keep the bose head because i don't want to change the look of the dash with an aftermarket radio, but I need to know if both these scenarios are possible, and if so which one is cheaper. Hopefully someone can help me here, thanks!