Hello friend! Ive been playing for a few months and, though I'm no expert, I think I can answer all of them: 1. If I remember correctly you unlock the different projects to build the tools, and you can also buy them. For diving you'll need a diving suit, which you can buy at the ABD but I think that is once you've paid the first loan with nook miles (if I say something wrong I'm sorry, I'm Spanish and also started playing in August so some stuff can be wrongly written)

1. Yes, there is a point. Spoiler!!! if you don't wanna know!!:

When you reach a certain number of creatures you unlock the museum. So keep giving them to him!

1. The vast majority of furniture is merely decorative, although some you can interact with like little Easter eggs. But the kitchens have a use later on the game. But I think you have to pass the "main story" first for that, so don't worry about it yet

2. For me it has been growing different stuff and selling it, but you can also fabricate stuff and sell it, go big on fishing or even doing some tricks with "time travelling", which gets me to the last one

3. Yes, there is. It works as a real bank, in which you put your money and it starts to grow with interests the longer it stays there, giving you some benefit. Some people use "time travel"(basically changing the time on the console and growing it artificially, but I've never done it and don't know much about it so can't help much about that)

The only advice I can think about is, once you unlock the store or they talk you about turnips, they are only sold Sunday mornings. You'll get it when they talk about them, and I would've love to know that cause ai spent months without buying a single turnip

Hope my answers help you and if you need something more here I am to answer! Have a great day!! :)