I don't know any specifics about how these companies do things, but this part of what they do doesn't seem like it'd be especially hard. The various music service APIs provide ways to search their libraries for a string so you could do a reasonable first stab that way. Youtube's API provides th...
I have a lot of background in live event promotion and also dealing with investors. Really it depends on the type and size of the event you are wanting to promote. Sometimes sponsors are enough to get you going depending on what the target market it is and if the ideal audience for the concert ...
Check out these WordPress plugins: https://wordpress.org/plugins/shardb/ and https://premium.wpmudev.org/project/multi-db/ Good luck!