The paper describes research needs in primary R&D areas for the family of dual-coolant lead-lithium (DCLL) blankets. Associated key scaling parameters are introduced and evaluated under conditions of FNSF, ITER and DEMO and also for the existing non-fusion MHD facilities, using the MaPLE loop at UCLA as an example. Comparisons among these parameters are recommended for measuring the R&D progress on the pathway from the present experimental facilities to FNSF. Possible experiments both in the existing facilities and FNSF are discussed along with the flow diagnostics.