I'll try to help as much as I can.. But there's members who are more experienced than I am. (I'm new, but I love slippers.)
About repotting, unless it's a picky plant you should trust your gut feeling. I usually repot all my orchids before I move them into my normal setups. Most the time the plants I get come in old bark, with bugs, or it's not what I want to use. Unless you know what the grower used (throughout the whole pot), you may want to unpot it and check the media and roots.
I thought my paph Ho Chi Minh was potted in just bark, but I unpotted and found a lot of sphag! I could have rotted the roots, or I almost did.
I like the classic paph and phrag mix, from Repotme. I haven't used it with a paph yet, but I can already tell that it's better than store bark. I used it with a phrag.
45% Repotme mix/ 40% LECA/ 15% sphag. I water it every 2-3 days. (Phrags require different care than paphs though.)
If you're using pots with several slots in it, just remember it will probably dry out faster. Some of the Repotme paph mix will fall through the slots too.
I repotted my paph sukhakulii and HCM in a mix with more sphag, but in slotted clear pots.
ETA: the owner of the greenhouse I go to said that paphs love to be repotted. (This might be an opinion, or could be true based on the growing conditions.) I've also read that some do not like to be repotted; I'm not sure which ones. My sukhakullii has new roots and a new growth now, I repotted it over a month ago. It seems happy
My HCM (delenatii x vietnamense) got mad at me when I didn't water it in time, but it's happy and grows when I keep it moist enough.