The model on its own can be imported, but not the rig, and depending on the software, the textures might not be transferred either, since i set them up in blenders node editor.

This model primarily works in blender. (but you can modify it to work in other 3d software's if you want)

yes

Most in particular.

 i usually use rokoko and mixamo.

You can use the mixamo addon which is free, auto rig pro which is paid for, and other ones you might use.

I like to use auto rig pro since its much more accurate and tends to have less issues.

mixamo addon: https://substance3d.adobe.com/plugins/mixamo-in-blender/

ARP (auto rig pro): https://blendermarket.com/products/auto-rig-pro