you dont NEEEED live rock. But it is a great idea, a really great great Idea.
Foam will also act the same as LR(I personally think better, but thats my opinion).
heck...a few bricks or cinder blocks in the tank can become Live rock given enough time.
Having Live rock is popular, and for good reason.
I dont have LR in my quarentine tank, My last group stayed in my QT for 10 weeks w/out rock or sand.
yes you need a heater. your room may be 76, but the tank will drop lower than that. fish only are fine in 74 degree water, but keeping it stable is very important. if you got a 40g tank, then you really only need a pair of 75w heaters at minimum. Ideally a pair of 100-150's since 3w per gallon is good rule of thimb. Since you live in texas, your weather will allow for slightly less that rule of thumb. and such a small tank size will realy impact how efficent your heaters are.
as for current, for now if your on a tight buget i suppose you can skip this.
But honestly how bad is it to get a cheap little something? fish do like to swim in a current, its like gym time.
Truth is its better to wait till you can afford to do it right, starting sloppy is not a good start