Does anyone know the actual percentage chances of getting each result?

+4
+3
+3
+1
0
-1
-2
-3
-4

If I want variable point costs for abilities and I own BESM 1st, 2nd and 3rd edition is there a simple conversion factor for using this material?

(Complete OVA newbie so pardon if this is an idiots question)

Just got the OVA main book. In the chapter on "Taking Action" it says to roll two dice. Where does it say what two dice (d20, d10, d6, etc). Also the examples mention rolling multiple dice. How is this adjucated.

Thanks