Can the HDMI work with non-4k HDMI cords?
Yes.
Can i insert sd/ micro-sd card and play the video on ipad pro?
Yes, it will show on your iPad file folder. You may need to transfer it to your iPad file folder first.
i had no clue what the PD port was for.
The PD charges the laptop fine.
If i plug a mouse into this adapter, will it work on my laptop?
Yes,it is compatible.