No. Realme X does not have the memory card slot but you should not worry about it because it comes with 128GB internal storage option, which is pretty big from a regular usage perspective. Besides, the mobile also has OTG support.
Realme X is available in 2 colors - Polar white & Space blue.
No. Realme X does not support wireless charging. It has USB Type C port for the fast charging.
Yes, Realme X does have a 3.5 mm headphone jack.