I assume you’re talking about dry hopping??? I use a stainless steel mesh ball and throw it in the primary (I gave up on racking). I feel safer (contamination-wise) using stainless steel over cloth. You can’t avoid sediment if bottle conditioning, but you can greatly reduce it by cold crashing...
I have found small droplet-sized clumps of gelatin stuck to the inside of the fermenters. I have only just started checking the temp of the water before dissolving the gelatin, maybe I have been dissolving it at either too hot or too cold a temp.
I have the exact same issue and also discovered only after several brews using gelatin. I thought about ditching the gelatin all together and only cold crashing, but my brew fridge has been hijacked and cold crashing is currently not an option. I find it best to clean the bottle ASAP after...