I think what you're going to butt up against is the budget. There are solutions out there, but not necessarily at your price point.
If it were me, I would also be spending some time checking out the laser - as I mentioned previously, I'm still not entirely convinced the scanners are going to be up to projecting the text when using true type fonts, and thats before you get into finding suitable software.
Given that you are projecting this, does it have to be a laser?
Moving to a regular projector and projecting outlined text will give similar results at short range, but you'll have a world of more appropriate software available to you.
I wasn't suggesting guessing - if you know the duration of each scene, and you know how long a LQ frame lasts for (or can be made to last for) you can work out how long it needs to be quite accurately. Ok, so not drag and drop from a GUI, but do-able nonetheless.i don't think guessing the number of frames would work for me.