@Brant, ask questions now! Don't wait until you need an immediate answer!
Sorbate is added to all kits as a preventive measure, to help beginners NOT produce purple mini-volcanos, which will happen if the wine is not fermented dry. Kit instructions are optimized for beginners who have no experienced help. If you are using a hydrometer and getting a low enough reading, sorbate should not be necessary for non-backsweetened wines. After bulk aging a year, you should be fine.
Add 1/4 tsp K-meta every 3 months and during each racking after fermentation is complete.
FWK Packet D is K-meta/sorbate, and most vendors appear to be combining them as of a few years ago. I date sorbate packages and drop 'em in a drawer. If I make a backsweetened wine, they get used, else I bin them a year or so later. Sorbate has a limited shelf life, and since I have no idea how long the packet sat in a warehouse, I exercise caution and bin them. It's far cheaper to buy sorbate as needed and NOT have to unbottle and recork a batch, and there's no mess to clean up.
I add fining agents right after fermentation, as it gets the gross lees out. Once a wine goes into bulk aging, unless there is a build-up of gross lees (and after fining there shouldn't be), I do not rack as it's not necessary. Fine lees is expended yeast hulls and can be left in. Look up "sur lie" and "battonage".
Filtering is NOT for clearing the wine, it's for polishing. If you have a cloudy wine, you will probably plug the filter, so use fining agents and/or give it time. I haven't filtered in decades, but when I did, that was done shortly before bottling.