need a bit of set-up advice

ive managed to create a log in script, and a predictions table where it stores peoples predictions for upcoming fights, ive also got a table that stores the fights/results

i know at some point im going to need to add values to the scripts so i can add them up,but ive got a few questions if anyone would care to help out

1. AM i better adding a score row to my user_predictions table and once a fight has ended, then transfer the score total over to the (table)'users' score row

2. How would i put a time limit on the predictions, for example, i only want people to be able to predict up to a day before the fight starts

3. How would i have the user_predictions table reset certain data based on conditionals when another table is updated

am i better making a seperat epost for each of these?