Yes but it doesn't work the same, you don't know what it is going to do until it does it. Try it on Chrome. It's a way more polished UI that gives you a dynamic preview. Makes a big difference especially on multiple monitors.
As for the other things (MIDI etc), is there any confusion?
As far as midi goes, that seems like a feature that is not implemented which is different from not working. That's like saying PDF isn't working in Chrome...
Firefox has robust tab dragging. You can drag tabs all around. You can select multiple tabs and drag all of those.