Two fans will probably be just fine. Your case should have one on the front for intake, and one on the rear for exhaust. For that rig, that should be plenty. I would just put the system together and get it running. Then you can check the temps as you go and if they are a little high, then add more fans later.
Cable management takes a little practice. Especially building your first PC. Good quality components play a big role in cable management. A case that has good cable routing and a modular PSU make life a lot easier. Looks like this is a budget system, so you may not have some of the higher end parts that make cable management easier. For now, try and route what you can from behind the case and use bring it back in near the slot on the mobo. Any excess cables you have try and leave them behind the case. Pending you case, you may have to lay it on it's side to close the back panel due to excess cables and wires.
Just go slow and you will be fine.