Pothos will get just as big if conditions are right. This one is supported by three pieces of bamboo tied together at the top. I had to move this plant about a week ago so the top foot or so has slumped over so one day I'll have to re-tie it to the poles. The small triangle next to the pot is about 7" on the short sides. Your smaller plant should be fine while it dries out for a week at a time. Mine I give about a gallon of water a couple times a week and I don't empty the drainage dish either, it sucks it all up in least then a day. Once it starts getting some size to it expect it to need about 2-3 feet of space from the stem so the leaves can open up and spread out. You can grow some smaller aroids in the pot to fill in some of the empty space. Give it bright indirect light or morning sun and bright shade for the rest of the day, keep it sorta damp all the time (with a fast draining soil) and use a good fertilizer. Gnats are a sign that your soil is too heavy and doesn't drain well.

I'm not an expert by any means but here's my experience with Monstera. I had a very large plant that I just didn't have room for anymore. It had climbed all over the front porch and I needed the space. I hacked (and I do mean HACKED) it back and dragged the pot into the back yard for the winter. The cutting were thrown into the compost pile and the pot was left to fend for itself. Well, the cuttings ALL took root. The original plant spent the entire winter with no protection in the coldest portion of my yard. In spring it jumped out like a jack-in-the-box. So, my experience with Monstera is this. It's indestructible in our climate. It roots like crazy and it will cling to and cover your house if you so desire. Note: This winter I'm dragging the original "monster" back under cover for the cold season. I feel ever so guilty for my attempted murder.

These monsters don't mind having their roots disturbed. I repotted mine back into the same pot. It didn't quite need to be repotted just yet, but the wooden stake I used had given away and my plant was now leaning, spreading outward because nothing was really supporting it anymore. So I wanted to straighten it out and use a stronger, longer lasting steel stake. Also, I wanted to prune away most of the potted roots and retrain most of the aerial roots back into the pot. When I unpotted it, the roots were so intertwined that I didn't even bother trying to untangle them. I used my pocket knife and just cut away at least half of the roots, maybe more. I straightened it upright, guided the aerial roots into the pot, and gave it fresh soil. Then I staked it up, using better supports, stuck it back in its usual location, and gave it a good watering. For now, most of the leaves are leaning to one side. But the stems are finally upright again, and it's slowly straightening itself back out. My hacking away half of its potted roots didn't phase it one bit. My monster has only continued sending out new leaves without even skipping a beat. As if it were saying, "Is that all you've got?!" HaHa...

You're right, if you cut off the leafy growth at the ends of the vine it will just produce more new growth at the end again. If you cut up the scrawny stems and plant them you'll get a lot of new growth and consequently a lot of leaves. But light levels need to be high. You must be careful with that, the losers (leaves) in the competition for light will wither and fall.