1. with how much Ampere does the original diver run

500 lumen maximun ANSI (OTF) = - 530/540 lumen out of emiter =- 1400 mA for a XM-L2 U2

Those are some very rough estimates.

2. does this setup work?

I have a Sunwayman V10R (original XM-L T6, the same driver that V11R) with a Nichia 219C 4000K, and it work very well

3. do the MCPCB fit into the V11r? I Somewhere read that only 12 mm or less fits.

Yes, máximun PCB 12,5 mm diameter.

4. if it doesnt work: anybody has another idea to get a real warm colour in the V11r, preferably with high cri?

The main problem is to “crack” the head of the flashlight without damage it.