Dev kit: it is under development currently. Making it clean and only keeping the essential engine files plus a few example characters/vehicles/buildings for a sample game. It works right now and the game is roughly between 10-20 MB, but i'm still cleaning it up and the examples are not finished.
Renegade on the Launcher: danpaul88 is working hard on Renegade support but he has little free time so please be patient. IIRC the plan is to allow the Launcher to detect your Renegade installation and use it to connect to XWIS/GSA Ren servers (so I'd guess whatever custom content you added to it will be in it naturally). So it will not download the game from anywhere as it is not freeware. No 5.x as it will stay on 4.x. Newer scripts versions do not support Renegade at all (this is why the code is a lot cleaner and easier to change, no compatibility required).
As for updating the game? I can't answer that, but I think it will be able to download and install the latest 4.x branch script updates.
Under-dev projects: we are pushing TS Reborn right now, fixing up the balance and some assets. This should be out this year but I have no exact date.
I'm also going to give a mega push to Apocalypse Rising this year. Whether it will result in a release or not I do not know, but major milestones will be met and the game should be very much in a Release-able state before 2020 I can promise this.