It's no problem, honestly, I ask(ed) lots of questions myself when I started
1) I plan to change it once a month or at least a portion of it.
2) I mist every other day but my ground stays moist from the waterfall drips
3) my water gets changed every couple days because of the cloudiness but I only use a gallon of water so it's not a big endeavor.
Btw the water feature helps a lot with my humidity.