You will get a color negative image but it may have dye stability and hue issues because of different CD. RA4 paper is something like 5-6 stops more sensitive to blue than to red, so I think you should use a warming filter even when using incandescent lights. Red layer is on top and probably there is no UV filter, so attach a UV filter to lens.
Yes, but I referred all to the other thread here on APUG which has more discussion.
Bujor B. used a "cross" process that was similar to one I had devised back in that time frame and published on PN. It will yield quite good positive "prints" from in-camera exposure and prints from slides if done carefully.