Sounds like you've got the whole seasoning routine down real nice. An alternative to all that expensive propane use is to get a Weber Kettle Charcoal grill and a couple 10 lb bags of charcoal. A full load of charcoal will season up 4 pots once, or one pot 4 times. Sounds a bit excessive for how long it took to get rid of all the packing wax, but it is what it is, and you do have to get it all off. Cooking it off is the best way I know.

3 seasonings on a new pot is a good start. Don't leave your cast iron with an unseasoned coat of oil on it. The oil will go rancid, turn gummy, attract debris, taint your next meal, and can lift off some of the seasoning beneath. If you've got your pot well seasoned, then store it that way. It will be fine for a good 3 to 6 months. I sometimes put a paper towel between the lid and the edge of the pot just to let a little air in once in a while and prevent condensation.

You'll know within the next firing or two of your pots whether there's a crack or not, unless they get unexpected stress (heat/cold, impact etc). Cooking in a pot that doesn't have a lip or feet is a lot more work, but having tried it you have increased your proficiency.

Kudos.