If a girl sometimes doesn't respond to a text, or is just real short with her answers, does this mean shes prolly just not into u?

from what you wrote, yes.

Do you normally give 2 worded texts to people you are interested in? Probebly not.

If your looking for indications in texting it is all about the responce and if it is worded in a positive way. (Hard to explain but pretty easy to recognize in real life). Best way to see IOIs is be creative in your text and see if she plays along.

For example I was talking (texting) a girl origionally from Maine and Im from Jersey and I was negging her about Maine being cold, shitty beaches, whatever. Every responce I got was long, well thought out, and I could easily give a responce back. All very good indicators.