The case does not have an integrated fan controller (fan hub) according to the available product data. The supplied fans (1x front, 1x rear) can be connected directly to the mainboard. For RGB control on models with RGB fans, a separate controller is required, which may be included in the scope of delivery depending on the model.
Note: The in-house data provided does not mention fan lift. Official Corsair resources confirm that the 4000D series supports up to 6x 120mm fans, but without an integrated hub. If extended control is required, an external hub or a motherboard with sufficient connections is recommended.
No, a maximum of 360mm will fit in the front, but only with difficulty. At the top of the case, a maximum of a 280mm radiator will fit. The RAM must be low profile (no Corsair dominator, but lpx is okay). I personally use a 240mm, then you also have enough space to lay the cables too nicely 🙈.