As you may or may not know, 24" studded tire choice is almost nonexistent. So I have ordered Halo Ception tires (24/2.6) and plan to screw in the tire studs myself.

My questions: can you recommend the studs to buy? And what exactly is the process of sticking them in -- do I need to drill holes for them first?

Thanks!

P.S.: if you know of any 24" studded tires that are at least 2.35 or larger, please let me know. Sadly, I could not find any.

They sell the marathon winters in 24x1.75" (not 2.35" or larger though). It looks like you can order it from the website directly:
https://www.schwalbetires.com/bike_t...arathon_winter

The Nokian M&G come in 24 x 1.9", they're officially listed on the website but not sure where to order them:
Tyres | Suomi Tyres

I suppose neither of those are 2.35" though.

If you want to make your own, I'd take a look at the stickied thread in this forum titled "Making Your Own Studded Tyres":
Making Your Own Studded Tyres

I’ve made studded tires using an old tire with a bad carcass as a donor.
For those you need to drill before pushing the stud in.
There are screw-in studs available but they can be kinda pricey.
And it can be difficult to find a tire with a tread pattern coarse enough to take them.