I played around with heart usage a lot, and it's a fairly complex matter, though I don't think it would have had any noticeable impact if I'd gotten every free heart on the way. There are a few enemies I could have killed fairly quickly, but it's more of an alternative to dodging than an improvement as it tends to take just as much time, and I have to take my recording setup into account, too, sadly. My "platforming grip" is different from my "battle grip", and mashing weapons in the middle of a jump tends to make me move the DS around too much. Especially in segment 2, there's no way I'd add another risk to Kalidus after getting past Ruvas with a Heart Repair.
As for the medals, well, I just get some while waiting for the orb, so they obviously don't cost any time.
As for the medals, well, I just get some while waiting for the orb, so they obviously don't cost any time.