Sounds like a plan!
Don't worry about baby mollies - most of them will be eaten (I know, but it's nature) and most local pet stores will happily take them. If not, and you happen to have a population explosion, I'll be happy to walk you through selling on Aquabid.
Do me (and you!!) a favor and do NOT look on online fish forums for advice about setting up a tank or stocking. There are some rabid folks out there happy to loudly scream endlessly about the delicate nature of the nitrogen cycle and that tanks are overstocked with 2 guppies in a 10g. It's awful.
I will tell you from DECADES of experience that it's easy to cycle a tank (and if it's not easy, you're doing it wrong), filters are a thing that works, you do NOT need ammonia and the uber-expensive test kit (I actually don't even own a test kit and have 4 tanks set up right this second) and nature is known for stocking fish pretty hard - in spring before they eat each other, you can practically walk across my pond on all the minnows and bass, the only thing they suffer from is each other.
In fact, real quick, here's how you cycle a tank.
Set it up, put a light on it for at least 10 hours a day. If you can get anything - anything at all - from a healthy tank, or even a clean stream or pond, like a cup of water or a rock, some filter media, drop it in and let the filter and heater(if you have one) run.
Three to 7 days later, go to the pet store and get a live plant. Make sure it's a true water plant, like guppy grass, cabomba, hornwort or the like.
A week after that, go to the pet store and get a snail, if none came with your plant. DO make sure that if you get a pretty snail, like a mystery or nerite, that it's been in the petstore for at least a week and that they feed them, so that you're not bringing home some poor starved thing about to die of shipping stress and then you'll blame yourself.
Once Gary has reigned supreme in your tank for a week or 10 days, bring home your first 2 fish, the hardiest ones on your list. In this case, cories. I know you want more that 2, start with 2.
Next week, bring home the rest of your cories.
Two weeks later, add another species, etc.
Basically just start slow, stock slow and let the water do it's thing. It is absolutely that easy.