Active 4-way help

I have been really considering upgrading my system to active. Have been reading all I can trying to learn but I've hit a point that I need to ask someone a question. I'm running 4 sets of speakers passively (1" tweeters, 2" full rangers, 6.5" mids, 10" sub). My confusion comes from looking at other peoples network diagrams. Each speaker needs its own channel correct? Each set of speakers needs its own amp correct? This is because the ranges from the DSP are separated to each amp but what i'm seeing is a people running the tweeters and full range speakers off the same amp. So it appears they are using a 3-way crossover setup but with 4 sets of speakers. Is this correct? Can I run my 1" and 2" off the same 4-channel amp? Sure would save me some money if I can.

Another question.... I like using an in-dash EQ to adjust between different albums. They are mastered a little differently and I can pick it out like nails on a chalkboard. Some times I want to bring up or lower the highs and having the EQ lets me adjust on the fly without having to dive into the menu of my HU. If I get a headunit like the DEH-80PRS that lets me run active without a standalone DSP crossover will that make my in-dash EQ pointless? I can't see how I could tie that into this type of active system if the crossover is done inside the HU. If I want to continue to use my EQ would it be better to just get a standalone DSP box and put the EQ in front of it?

Thanks