I have an account and was thinking of making one for my band, but I don't really understand some things about Twitter and it seems like most of you are Tweet savvy
So I follow people and it seems that it's all spam, and even if it's something funny (like Tom and Tim H's tweet "fight" I "read" later by watching that animated version) how do you follow that if you're following a bunch of people who keep posting crap? It's just endless scrolling? or searching for someone every few minutes?
The Mute option is your friend. Mute the people who are posting too much crap. You're not unfollowing them, and you can still chat with them on things you like to hear or talk about.
Why do I mostly see people replying to people I don't know, and why would I care about that? can that be filtered out?
It's Twitter's way to finding new people for you to potentially follow... just like in FB. That's the price you pay for having a free social media thing. There might be an option or preference you can set to change this, but I've never used it.
What exactly is "trending". It means it's a popular hashtag? who decides what's trending, does the tag have to get repeated a set number of times?
Pretty much. Twitter decides this stuff. Though I'm sure some companies pay for certain Trends to go higher up than others.
How do people even get followers? by hash tagging?
If you tweet something people like enough to retweet, that's the best way to get new followers quickly. There's a chicken/egg issue if you're brand new, in which case, you may need to use hashtags at first, if being Twitter royalty is the end game. I've been on Twitter for 6 years, and I'm only at 500 or so followers. I never had any ambitions there, and yet over time, I still get new followers. It's a long game if you're just there for fun or boredom relief.
It seems like Twitter is a mess, but people love it and use it constantly, so I must be doing something wrong...
Social media is a mess. And you're doing nothing wrong, at least based on your questions above.