I have a PS4, is there a DLC for Mount and Blade warband: napoleonic wars, or is it just a rumor?
and is there the DLC for the PS4?
No, it's not a rumor. You can buy the DLC on Steam (see picture), but unfortunately I didn't find the extension in the Playstation Store. This is probably only for the PC.
Does the game need a lot of space on the computer? I also have a laptop. The laptop is not necessarily one that is made for gaming, for example, the OptifineMod for minecraft didn't go particularly well for me (there were always small stutters). Do you need a gaming laptop for the game?
Do you need a gaming laptop for the game?
I don't think so since the graphics are pretty outdated.
I would recommend you to compare the https://systemanforderungen.com/spiel/mount-and-blade-warband with your laptop. Then you can directly see whether he is packing the game or not.