Growing a few plants for the first time in my basement need advice

I'm looking for some help like links, Reddit posts, or websites for instructions and tips on growing marijuana for the first time. I have a few plants just a couple weeks old and I have a few plants that were given to me that are a 4-5 weeks old, not too big yet.

When do I know my plants are ready to flower and to change to a 12 hour light cycle?

When should I start using nutrients and stuff other than water? Is tap water okay?

When the smell becomes over whelming and they need to move to the baement, will the cold be an issue? Will it still smell upstairs?Should I have a grow box to control the smell?

And lastly I'm not sure if the plants I've germanated are males, how can I tell? Should they be moved or do I want them to pollinate the females?