Yes - but don’t feel like you need to rush out tomorrow to get it done. Unless you are planing on being a social influencer and posting 1000x a day including controversial stuff then you probably have some time to interact and grow the network.

It's generally anarchy, although it's best practice to pick a kind that you don't see anyone else using.

If you want to avoid creating clutter, or if you want a good testing environment, you can use a local relay- like nostr-relay-tray.

There are also a bunch here https://github.com/aljazceru/awesome-nostr