The system will use the pools in the order that they are in the ARS tables. So change table 25, the default LD table to use pool 890 as the first choice, and 70 as the 2nd choice. It won't go to 70 unless 890 is busy. You could also play around by raising the FRL of 70 in pool 25 to 4, and giving a FRL of 4 to the "big bosses". They would be able to access pool 70 for LD if 890 is busy, but us "regular" people would get wave-off if 890 was unavailable.
Conversly, add 890 as the 2nd choice for the default local table, so if 70 is busy, you can fall back to 890.
Create a brand new table for the toll free numbers, again using 70 and then 890. No sense sending toll free calls over the cheap LD lines, unless the other lines are all booked up.