How do I get cat to get along with kitten?

Hi, Reddit. I adopted the resident cat from a home that was fostering 11 other kittens so I figured he might love another cat. He has a great big personality, very affectionate, high energy, vocal. He's a big love. My resident cat is 18 weeks and my new kitten (sweet, maybe a little timid[?], goes bananas when it's time to play) is 10 weeks old.

I got the kitten a few days ago and within the past couple of days, she seems to have gotten over what the breeder referred to as "separation anxiety" peeing (i.e. peeing on beds, NOT going in litter even when I place her there pre/mid/post-pee). Resident cat still growling and hissing at the kitten. (Currently both are NOT neutered/spayed; awaiting vet appointment to neuter my guy; female kitten too young right now. I DO plan to have both "fixed".)

My main concern at this point is getting the resident cat to stop hissing and growling at the kitten. Kitten will hiss back. Nothing ever escalated into a fight. At this point, the cat will consistently go over to kitten, sniff around and then growl. Cat probably swatted at her once in these whole three days. Right now, they're running around and chasing each other (no violence, just chasing with minimal growling, some hissing, some "brr?" trilling - not sure what to call this sound). Does this look like it's taking a step in the right direction, or is there more that I should be doing to facilitate the relationship?

EDIT: I've used a feather cat teaser between them. Sometimes resident cat goes ham on the feather and bites/attacks it, growling.

TL;DR: Resident cat (18 wks) hissing and growling at new kitten (10 wks). Currently chasing one another back and forth, making trilling sounds, but still ultimately hissing and running away - rinse and repeat. I want to make sure I'm setting the relationship up for success. Ideally would love for them to be a harmonious kitten pile.