Should be 6 slots on the xover.
One set will take + and - from the amp, the other two sets you'll run speaker wire from and into your components. It'll be easier once you see everything in person.
Just think of the crossover as a divider. Basically it just separates the tweeter signal from the midbass signal, and delivers it to their respective driver.
Also, what you could do is just mount the crossovers near the amp, and just run speaker wire from there up through your truck, and into the components.. Just make sure everything is labeled + and -, and tweet or mid.
Also, I don't think you'll need more than your single sony for those components.. It would be hard to match up the amps so the sound came out exactly the same anyway.
If you feel like you need more power going to them, or if you feel like the sq could get a little better, just pick up another 2ch amp that'll do 100wrms per channel. The only amp I've run for speakers is an xtant amp, and that thing is super clean. There might be better out there, but I've never used anything other than that.
Just ask around and get some opinions.
www.caraudioforums.com is a good place to start.