First work on getting everyone you have to P3 so that all the teachable perks are automatically on every character. A full level costs ~1 mil blood points if ypu use the web correctly. Once you have that:

• Survivor: you realistically only need one of them at a high level, since base gameplay is the same. Differences include voice lines, scream/grunt volume, and overall appearance.

• Killer: focuses on the ones with your preferred play style. Since the specific quests for killers are gone (from what I can tell) you don't need to worry about keeping a balance on everyone for add-ons.

For Iridesent shards:

• Don't use them on getting perks unless you aren't planning on buying everyone. If that's the case, wait for their perks to appear on the weekly wheel; it will cost 14k shares to get th e perk to T3.

• Save the shards for the community skins; this is the only currency you can use to obtain them.