Privateer,

A lot of wise information and advice there. Glad to see you're winning.
I'll just add a couple of things which may help some punters.

The beaten margin is far more accurate in assessing a horse's chances than actual placings.

Average prizemoney is more powerful if you use the average prizemoney won over the last three starts and compare it with the overall API.
The last three starts API should also be massively larger than the career API - if it's not then your horse is in very poor form!

Barriers have very little to do with a horse's winning chances unless you can specifically pick out a reason for a barrier not suiting your horse's pattern of racing.

Average lengths beaten over last three starts is far stronger than lengths beaten last start.

Track and distance stats for your horse are pretty useless UNLESS you assess the failures rather than the wins.

Did you know that less than 15% of races are won by horses with 100% track or distance record?