would typically tell you anything they need to, to sell you something. They would tell you a shark would be perfect for a 20 g, if they were selling you the shark.
It takes years to build a somewhat trustworthy relationship with the typical LFS
Your best bet, is really to research on your own and ask questions on sites like this one. No one here has anything to gain by what they tell you.
Like we discussed on the other thread, T8's really aren't enough for coral. And 2 small T5's would only be able to do soft corals.
Just a suggestion, but maybe make this tank a fish- only set-up, then lights don't matter. This would give you some time to see if you really want to get into the reef side of the hobby. I would try to trade the buttons for a fish that you like, or keep them and see how they do