Grrrr... those mallsai! Chopping the top won't make it grow taller, only bushier. Planting it in the ground might help, but in Houston, you'd have to find some way of keeping it moist and humid full time. You almost can't give it too much light for too long, but you shouldn't have a problem there, but full spectrum fluorescents might help if you grow it inside and keep them on 16 hrs/day. Yes, the little pot (til it's the size you want in future) will restrict it. Don't cut roots either when you're growing it out, but put a tile or something under the middle to spread roots and keep them from growing downward.

Thanks, Lucy. I think I am going to put it in a large enough pot so that the roots can just go crazy. The tile is a great idea. I never thought of doing that. It is amazing what you learn here. Would I need to use the same potting mix as in a bonsai pot or could I use something a little more water retentive? So, do trees grow from the base or from the crown? Why isn't this guy getting any taller?

They grow from the crown (apex), while still putting on weight lower down (sounds all to familiar to me :-). I don't see why you would change the mix unless you're planning on putting the pot out in the sun all day while you're at work (and I wouldn't recommend that). A lot of people use 'training pots' which are basically wooden crates of whatever size, made out of slats but with screening on the sides to encourage roots to grow outward, and they're apparently very effective, Any roots that grow through slats on the bottom or sides are just chopped when removing the tree in future. I have to tell you I don't know whether or not those tree chops have been treated with something to maybe make them stop growing up, and just grow sideways (to look nice and fat) but I wouldn't put it past the bonsai 'factories' to do anything! What you could do (do you have a good pair of concave cutters?) is try to carve/chop the flat stump into more of a pointed roundish one, and see if anything changes (if only by your having removed the flat end. But you also might want to ask Jerry Meislik first as he's the ficus expert - www.bonsaihunk.us/cultural. Be curious to know what he says!