With regards to the lighting, obviously everyone has preferences regarding brand and even LED vs T5 vs MH, etc.
However, with the tank's size I feel you could get away with many options from a Kessil 360, a AI Prime HD, or Radion xr15. Again with the size and shallow depth, any of these lights would be able to grow out about any type of coral.
With regards to plumbing this to your main system, my question to you would be: What is the purpose, or your intents with this frag tank.
Is it for grow out for your main system?
Is it for quarantining corals prior to moving to main system?
Is it to frag corals from your main system for recovery, then trade/sale?
I asks, because if it were me, I would keep the frag tank as a stand-alone if it were for quarantining, however, most likely look to plumb in with the main system if it were for other reasons.
Also.....your choices, or purpose of use for this tank may influience what lighting you decide on as well. For example, you may want to 'match' the type of lighting to your main system, if that is its' purpose.