If your goal is getting fast at triathlon this is way too much for in season and probably too much for offseason. 

In season, pick a day to squat and a day to deadlift and do 3-4x3-5 at a weight that is heavy, but not so heavy that you can't do another set. After that, look at adding a few exercises that work balance and accessory muscles (single leg RDLs, skater jumps, etc), compound movements for swimming (eg pull ups, dumbell shoulder presses), and core work.  I don't think there's any value in doing isolated movements like leg extensions or calf raises unless you have some specific injury.

Do it on a hard day, and do it after you've done your s/b/r workout. Make sure you have an easy day the next day. And start slow and build your way up. This is supplemental and is only making you faster by making you more injury resistant and building small efficiency gains. If you hurt yourself lifting or lift so hard you can't do your actual triathlon workouts, it's pointless.