The key to getting a successful harvest from autoflowers is?

A true autoflowering strain has a pre programmed lifespan: from the moment the seed cracks to the day she dies the age is indeed pre-destined  … therefore more than any other type of cannabis the vegative growth is critical to the end yield. If you are growing autoflowers indoors we suggest you raise the light during late seedling/early veg growth to encourage the plants to stretch out tall. Don’t worry too much about your node space, autoflowers are vigorous and they can cope with this.

Never Transplant!!! Start off in the harvesting pot 3Gallon+

You Could!! Cut off the bottom to a party cup, an when the roots come out the bottom just put the Cup in the bigger Pot.
20/4 hours is the best(Depending on Strain) If you really want to Find out what is best, Start with 24/7 then the next batch, use 20/4 and see how that goes