We want to drop off our luggage and use the parking lot and shuttle on Friday morning before allowed check in time, we will have a reservation for that Friday night, will this be allowed?
Sorry, but will have to check with the hotel specifically. As a local resident whose only stayed there once, I do not know.
Yes you can.
Luggage drop off and using parking lot should be fine (it was for us, and reception is open 24hrs) but you will need to pre-book the shuttle; I assume this is the Disney parks shuttle. I suggest you email the hotel to pre-book and then you can confirm use of the parking lot etc. The KBF park is a 5min easy walk from the hotel / parking lot so no need for a shuttle to attend the park.
Get an answer from Knott's Berry Farm Hotel staff and past guests.