No problem, if you wanted to set up a media stack there are tons of guides for it, but if you're curious, the guide I used was https://zerodya.net/self-host-jellyfin-media-streaming-stack/ it's down right now but there are some waybackmachine copies if you wanna have a look.
You don't have to set the internal IP of your server for connecting them together though, just put the name of the container, docker automatically points it to the right IP as said in https://docs.docker.com/compose/networking/
I prefer to use qbittorrent since transmissions development was paused for a long time so it doesn't have all the features of a modern client, and besides I was more familiar with it anyway.
I also reccommend trash-guides.info to get the best configs for sonarr/radarr/prowlarr
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