My Sony A7iii fits in with the Sigma 100-400 attached when I turn the tripod collar. Then there is still room for eg a 28-75 Tamron plus small items. 

hello,it can fit sigma contemporary 150 600mm.the compartment inside the backpack is removable, you can DIY according to the size needed. 

Yes it can. The lens would have to go in the main part of the bag if you are putting a camera in the bottom. But plenty of room for the lens and clothes. 

You can control camera shake by using your mirror lock, camera shutter release and cable, tripod securely tightened and all legs as squat as possible. The higher the tripod the less stability you have, but you can always attach your camera bag to hang on the hook, located on the bottom of the tripod to act as a center weight. And lastly, if you do not have a camera shutter release cable, the higher your Shutter Speed the more you will be able to control the “camera shake” or blur in your photos. I hope this helps. 

I don’t think so. I night this to use on my Nikon D3100 with a Tamron 70-300. Neither are very heavy but this head would not keep my camera still. It crept down no matter how tight I made it. I think your camera and lens are heavier so I would go with a better name brand.