Answering in order...
Cloning labs is a very different design, it focuses on collaboration and it gear checks players at the high end of the spectrum. It features harder versions of things you have seen before and it does have some new art but also uses some existing things.
No idea about new takedowns but i will ask
Saw the suggestion about photo mode, we are talking about it
Possibly its something we are discusing
Saving loadouts is on our list, not sure when
Loot as a whole is going to need some changes, thats one of the vectors.
No plans for a new difficulty at this time but we are introducing Omega Threat level missions with cloning lab, effectively its a bit like a new difficulty but no plans for something like more challenge levels atm.
Warzones currently only support very limited respawning but that's something i am extremely interested in. What you are describing is something i want to do in the near future.
That's part of what we are looking at for loot.
Not sure about new harm room features but someone is looking into improvements, ill ask.
No plans for an endless mode yet but i really like the idea.
Hope that helps answer some of your questions, you should try asking them on stream sometime so others can hear the answers!