No, Loki hurting Harald never happened.
Everything Loki did to him was instantly regenerated which means he couldnt even match Rocks' feat against Garling when regen was slowed down significantly.
Second thing, we have no clue why Imu's control was interrupted. You want to credit Loki's haki but the fact remains that we have no idea why. In fact, when Loki was slapping Harald around no haki was used to begin with.
No, living longer doesnt make Harald stronger, this is the same nonsense people said about Kaido in last 20 years. When you are in prime and you possess aCoC, there is no more strength waiting for you in 10-20 years.
HK is inferior to DR, Imu confirmed this himself when he demonified Giants. Bigger drawback results in bigger rewards.
Loki dominated Harald physically, that doesnt place his feat above Garp+Roger feat, lol.
Once again, the biggest difference in their feats is that Rocks didnt drop his haki defenses while Harald did and that makes Loki's feat extremely lame, on par with Garling killing Rocks.
Wrong, Garp+Roger are the first ones who killed a regen user because DR also grants regen.
Loki's aCoC is not above Roger pirates, it is exactly the same haki.
Imu is shook because he had a covenant forged with Harald while he didnt with Rocks and it has a drawback for him. It is a matter of reading comprehension...