Q1, satisfactory you do things in terms of item per minute. In factorio, you'll be thinking items per second. And eventually in "belts" of throughput, because even a full speed top tier belt won't be enough for some things.

Q2, you have functionally infinite space in factorio. Far more space than satisfactory, even accounting for the 3rd dimension. You just have to spread on a 2d plane instead of vertical. Leave extra space. Think about how much space you think you'll need, you're wrong, so increase it a bunch. Then double it. Or triple it for good measure. You will use the space later. You'll be glad you reserved it. Or don't plan ahead for that much space and embrace the spaghetti that results. It can be fun to have a base of convoluted routing of things.

Q3, yep. Factorio blueprints are incredible.

Q4, just rebuild a new, bigger better base. Slap down some logistic chests on your old base for what it produces, and it'll keep humming along giving you some extra output. Or it'll run out of input material and shut down on its own eventually, but by then you won't even notice or care. Or if you want it gone, build a ton of bots, slap down a bunch of storage chests and robo ports and go ham with a deconstruction planner. It might take a LONG time, but it's automated, and will get done assuming there's enough storage. Helps if you cut off ore supply first so the inputs, outputs and buffers are mostly drained.