Do I have to transfer out of primary to add finings

My English Draught Cider has fermented real dry and has dropped almost crystal clear. Was going to add K sorbate and K metabisulfate to shock yeast and likely cold crash for a few days prior to kegging and potentially back-sweetening some.

Should I transfer off of the yeast, or is this like beer where I can go from 1 vessel to keg if done carefully?

Was planning on dissolving both prior to adding if that matters. Also, do I need to stir them or will the diffuse on their own like gelatin? On that subject, should I add some gelatin as well?

You don’t have to transfer it, though I always do because I feel it gives a better, cleaner result.
I do it for both my ciders and my beers. In doing so, I get virtually no sediment at all in the keg…even down to the last gurgling pint.