Hey there.
About the streaming/recording stuff. Before streaming/uploading videos I would recommend making some friends in game. Joining multiplayer lobbies, opening randoms PM chats on osu!, then when you have made some friends you can share with them your videos, if they like them then you have a base!
Also, for the streaming part, I recommend you to stream on Twitch since YouTube doesn't get that much people watching osu! in livestreams, in case you want them to be in YouTube you can always reupload from Twitch (there is an automatic option for that).
Another tip for your YouTube channel, make it clean, use similar titles, don't use much symbols, people prefer to see a simple and clean title than a overloaded one. For the thumbnails, you should use very simplistic thumbnails, they look better when looking for videos.
Now the software part, for streaming you should use OBS, you already know that I guess. For recording I think NVidia ShadowPlay is the best (in case you can use it, if you don't then just use OBS, but this one is worst for recording). Another very important thing is the copyrighted music, be careful about that since YouTube is being very strict about this.
And the most important thing: do something that people want to see. Making videos of your plays won't get that much visualizations, in case you want to record and upload them you shouldn't do it on public, just to yourself on private. The content people wants to see is people doing incredible things, big and interesting projects, facts and tips from the game, that's why the recopilation channels are famous. Anyways, if you want a channel just for yourself and not the others, that isn't very important.
I think I said everything that can help you. In case of needing something or having a question, you can PM me