best money management strategy

Horse racing
average 9 horses per race 5 race leg sequence(fields range from 6-10 on average)

Question 1
best money management for long term ROI on this exact type wager the pick 5

Question 2 what win percentage needed to be profitable

Question 3
Is it best to single leg one of the 5 legs or over time pick multiple horses per leg or?
for best possible ROI

Question 4
Formula for best cost per ticket over a large sample for positive ROI

Average ticket cost range $750.00-$1250 US

example below random numbers and odds
Race (1 ) 2-3-4-5-6-9 Race (2) 4 (3) 2-3-6-8-9 (4) 1-3-5-9 (5)1-2-5-7-8-9 ....6x1x5x4x6= $720 cost
example Last 5 races Tampa Bay .50 cent US over $2500 pay off

Also want ideas on building a private database for private project files API ,XML and TEXT charts available