@Balls2wall I’m new to this myself but I’ll give you some of the answers I’ve seen around the forums that are most consistent.
1- top early if you’re going to top, like as soon as the plant has 4-5 nodes, and probably just once. After that FIM is safer
2- I need to know more about your lights. I have a pair of VS1000 lights, which translates into 100ish actual watts per light. I pretty much need both of them for one square meter. They claim to have a flower footprint of 3x3 each but I quickly learned that’s nowhere near enough light for a 3x3 space.
3- I’d use a 7gal pot - more soil = more available nutrients from the dirt without needing supplemental feedings and less watering.
4- I have 3 autos next to eachother and they’re fine for right now but they’re small. The general rule of thumb with plants is that your yield is based on how many square feet/square meters you grow in and not really how many plants you have. That’ll be a little bit different for autos but I’ve seen folks here grow some pretty big ones. I wouldn’t really put them any closer than one plant per 1x1 square and be prepared to spread them out if you need to.
5- get nutrients that are common deficiencies. I picked up the Fox Farms liquid nutrient trio (big bloom, tiger bloom, and grow big) and have used almost all of them about 3 weeks into growing (5 plants so it makes sense). Lots of folks around here use Jacks 321, that’s where I’m switching to shortly. Anyhow, get CalMag because no matter what you’re going to need it. And your FFOF will have nutes in it for 3-4 weeks before supplemental nutes should be necessary. But check what your plant says - they’ll let you know if they need more.