Hello, kindly tell me the type of cider to use… filtered, sweetened, unfiltered?

There’s no such thing as filtered apple cider. If you filter cider, it becomes apple juice. That’s all cider is, unfiltered apple juice. I’ve never seen sweetened apple cider, but no, that’s not what you want in case your local store carries such a thing.

For sure unsweetened, but I don't think filtered vs unfiltered will make much of a difference. Whichever you prefer to drink! (For me, unfiltered.)