Looks like small frags of pretty common corals, so price is ok, not great. Shipping costs a lot for overnight livestock so that's something to consider. I couldn't find anything on google for fluval G2 LED? If there's no optics, which I don't see any fluval leds having, then no, it's not enough light for these corals. They may stay alive for a while, but will not grow and thrive in the long run unless it's an extremely shallow tank. You might want to stick with mushroom and soft corals like leathers.
Corals do no affect the Bio-load for a tank so yes, you can add a bunch at a time. Where you need to be careful is with adding too many fish at once.