Each fish will vary with holding or "parenting" I've had 2 females (first time holding) swallow their eggs (one actually swallowed 3 broods in a period of just a week), while the 3rd one held just fine for 18 days until I stripped the fry.
10 gal would be fine, even for 2 smaller females, just put in some rocks (or whatever decoration to give them place to hide).
Unless the holding fish are being chased, nipped or get any sort of aggression from other tankmates, I'd let them stay in the main tank, at least until you're ready to strip them, if you choose to.
You can actually do a number of things, if you don't care about saving all the fry, just give the females a few piles of smaller rock, so they'll feel safer releasing them and not worry about other fish feeding on the fry. If you do want to save all of the fry, either separate the female and let her spit naturally and then return her into the main tank, or strip her when the fry are free swimming (usually around day 18 of her holding), transfer the fry into the grow out and the female into the main tank.
Usually when trying to catch a female early on (at least in my experience) results in them either dropping or swallowing the eggs, so doing it later, when the eggs have already hatched would most likely prevent that.
As far as catching them, try doing that at night when the fish are "sleeping" (a few hours after all the lights are turned off) and don't react as alert to the net as they would during the day, but there's always a chance that you won't be so lucky and would need to take all the rockwork out (if you have a huge pile), to catch them.