for the drum set u can try using steven slate drums, which has a free version thats still quite a good library (tho i havent used it much myself) spitfire labs and piano book also both have some drum kits that r pretty good, tho not as comprehensive as steven slate drums
as for the silence, that is a bit strange. i do know that this often happens when u have reverb on stuff that leaves an inaudible tail that the daw still exports. so i sometimes do an automation on the master volume at the end of tracks to make sure that it goes to complete silence where i want it to end. maybe thatd work? o well, better luck next time ig lol. it didnt take away from the quality of the submission anyway