Before I spend valuable real estate on a guild hall, I would like to know why it's a good idea.

I know I can share health kits, but I get by fine without them.

I know there are guild vs guild challenges, but I don't know how those work. Do they help your team grow faster? I find playing a league match and a tournament match daily plus some training is as much as my tram can handle.

Is there a way to share/trade players or get extra training?

It's good for advice, socialization, heal kits, money and experience from gvg, and many more things.

No player share and no extra training except gvg

How does GVG help compared to trained no matches? How does money come into it?

I don't know the exact math of training from matches. But for every match in gvg you get the same amount of cash as for a tournament or championship match. You get to challenge twice and can be challenged 0-lots of times per gvg so the cash can add up quickly.

Training points received in the gvg is very much the same as the training points received for a training match.

Is it worth building a guild hall and joining a guild?
A definite yes. Its a great way to learn from other players. You might not be using heal kits right now but as you move up they will greatly benefit you.

I agree with the lads on here Guild hall is not a waste especially as you go up the ranks people will hurt your players more so you will require more health kits and tactical knowledge of the game. Also if you don't like the bonus you can make extra money on the guild challenges and you get in money what you'd get for league and tournament if you want to upgrade fast joining a guild is one of the best ways to max out things fast.

Never mind not being a waste, the guild hall is what you should have been playing towards getting as quick as you could from when you started, its the most important building after your stadium, apart from all the heal kits you can get from guild members and millions you can make in each guild match you will also learn a lot of things by reading messages and asking questions in the guild chat..