The max weight would depend more so on what head and what legs you you choose to mount this quick set device onto.

This clamp accepts both traditional/regular arca-swiss plates as well as slidefix plates. Regular arca-swiss slides into the top dovetail whereas slidefix sits on the bottom dovetail. I've linked a few plates below, but for the regular plate all brands that use the arca-swiss compatible dovetail will work as long as their safety screws don't interfere. Regular: https://www.bhphotovideo.com/c/product/116072-REG/Arca_Swiss_802209_Universal_Camera_Plate_1_4.html?sts=pi&pim=Y https://www.bhphotovideo.com/c/product/822279-REG/Sirui_BSRTY50_TY50_Arca_Type_Pro_Quick.html Slidefix: https://www.bhphotovideo.com/c/product/663115-REG/Arca_Swiss_802283_Slidefix_100_QR_Camera.html

The plates are interchangeable. They should be the same size, but I would always check to make sure they are snug before you let go of the camera equipment.

The original quick release clamps on Arca-Swiss heads such as the D4 are attached without the intent to be user-interchangeable. There are reports of damaged clamp-attachment screws from those that have tried removing the clamps. We recommend leaving the original clamp attached.

Yes, it has a 1/4-20 or 3/8" threaded hole to attach.

Can slide out both ways or just inserted from the top, the clamp when open is quite wide.

Should work. I use Promedia Gear L brackets and they work fine. There is a degree of adjustability in the clamp.

The Camera base plate ( sold separately ) slides into the Arca Swiss Quickset Fliplock from the side, then clamps to lock