Yes, the front rotors are the same diameter, thickness and offset/height and are interchangeable between early Defo and D1/RRC. Ø298mm x 14mm thick with a 70mm height. Also, if you want to go to vented you can get vented rotors and space the calipers you already have with a kit from Zeus (UK), or LRA, Graeme Cooper (in ascending $$$$).
Yes, the solid D1 fronts can be used on the rear, if you use the matching Defo 110/130 rear calipers. Not compatible with the std D1/RRC rear calipers (different diameter (Ø290mm) and thickness (11.7mm)). This should rebalance the brake system however your brake pedal travel will increase even more (moving more fluid as the Defo's use 26% larger pistons than D1/RRC).

