First question, DMX is limited to 32 units, be it fixtures, dimmer packs/racks, and/or foggers and/or hazers. So you could have 2 dimmer packs and 30 LED pars on a universe. Also be aware that each universe is limited to 512 channels and how many channels your console can control.
Next question, you simply extend the DMX chain to include the LEDs. On each LED par, it will have a DMX In and Out just like the dimmer pack. So if you have 10 LED pars, you need at least 10 more DMX cables.
As for which console, would you like to just run faders up and control the lights that way and/or do you want to make scenes aka looks and/or do you want to program whole shows and simply hit a button to advance through scenes? Obviously, they increase in price with functionality.
A
Magic 260 is great for making scenes and shows which are a series of scenes with a set time in between each one. A
DMX Operator 192 is a bit more conventional in that it has faders and scenes like the Magic 260 but can't make shows like the Magic can however. Also, to link with the above, a Magic can control 260 channels and an Operator 192 can control 192 channels. Both only have one universe.
Let us know what you are thinking and maybe we can narrow it down a bit more. Also check out the
FAQ on the forums, it answers a few of your questions and hopefully a few more.