I think instead of answering your questions it will be more helpful for you if I just ask you a few questions instead.
What's your tank setup like, size, type of lights, substrate, ferts, co2, ect.? Those are going to be big factors in all of your questions.
In general, if you want a measure of light, go with PAR ratings. In general, low light is 15-30 micromols of PAR. I wouldn't go any lower than this for growing any plants tbh, even if they could grow just doesn't seem worth it.
How do you determine PAR? Well, if you want to be precise you use a PAR meter...but that is some $$$ stuff even if you buy a DIY one. Me, I use rough estimates (cause I'm classy like that). If I were you, I'd look up on google "How to light a planted tank with PAR" and read the first link...specifically the updated thing it brings you to.
Now, depending on your lighting, that determine how you are going to have to add nutrients for the plants, since the growth demands that the light gives the plants will need nutrients to fuel, otherwise you get a bunch of unhealthy plants which isn't good.
Combining nutrient and light needs, that will change how fast any plant will take hold in a tank. But even then, so will the placing of the plant in your tank. My leopard val is struggling because its closer to some crypts than it probably likes...and its small and having trouble getting the light it wants to get.
As far as runners, the plant will produce runners regardless, but if those runners will take hold and actually grow into new plants or wither away depends on how well they can get their roots into the substrate. Can you show a pic of your tank?
As for getting your plant to grow fast, all it is really is time. Aside from that, plants grow faster with more light (provided your nutrients and co2 levels are appropriately adjusted to the lighting) so that's more or less all you can do.
