If you want to failover policy routed items you need to create multiple failover pools, this has been discussed previously, so if you need details please search.
Ratios can be configured by creating a lb pool with multiple entries for the same line, ie-
dsl
cable
cable
cable
Then it should round robin between the four entries, Hitting the cable 75% of the time. Not that I've setup pools that way, usually having roughly equal connections…