lifting heavy is when you max out only on 1-2 reps
it's often very close to 100% of your maximum strength
the time it takes to complete the lift doesn't matter

powerlifting is usually a much lower percentage of your maximum strength
around 5 reps
try to complete the lift as quickly as possible

if you can gain the same potential without having to lift weights there is no benefit
it's all about power:weight ratio

recovery time is extremely important when you're doing weight training (ie gym time) and sports-specific training (ie court time)
schedule yourself light and heavy days for court time
on the light days get in gym time after (ie short court session in the morning, gym at night)

but yea, an actual program needs to be customized to the athlete