I really like the app Tunable. It has options for just tuning and also other more "exotic" tunings like Kirnberg lll, that work better with the gurdy than the standard equal temperament. If you ever intend to play with others also get a cheap clip-on tuner since it's easier to tune your Instrument with this in loud situations.
Sorry to hear my dude :(
One thing you cannot fix is that it is diatonic, so no flats or sharps for the Gurdy.
Do they offer returns? I'd try to take that route first, otherwise maybe someone can offer you some advice. It also depends on what specific problems it has. You may have to true the wheel, or file or shim the bridge, raise/lower the nut (it doesn't look adjustable). The tangents look like literal Terminal Connectors, replacing those would probably help.
I've never tried one so I can't be super specific.
If the crank isn't straight you can probably replace the whole thing. Better strings would probably help.
If you decide to invest money in a different instrument, the Nerdy Gurdy Basic is like $700 and highly recommended as a budget instrument.
I come from classical singing (as a hobby) where you can "cheat" more by just listening to the MIDI. Because of that I'm not very good at music theory and reading sheet music. But if you have a musical ear and a basic understanding of music theory and sheet music you will learn quickly. I even know some people who can't read any sheet music at all and play the gurdy exclusivly by ear. But I would definitely recomend learning to read notes. I made myself a cheat scheet with all the basic music theory stuff which I keep forgetting.
You can use partitions written for other instruments, but if you want to play with your drone strings you have to consider the key. I asked a question on this subreddit about sheet music some time ago (there are some links that might interest you).
So just to make certain, you are suggesting the light rosins that those brands make, right? Kaplan's dark rosin will still be pretty soft, so I should try to avoid it?
I highly recommend that people use inexpensive viola strings, especially when the instrument is new and you're just getting it set up. Strings do get broken during that process. I buy viola strings, 2 sets at a time, on Amazon. Here's what I buy. https://www.amazon.com/gp/product/B085BM1YNT/ref=ppx\_yo\_dt\_b\_search\_asin\_title?ie=UTF8&psc=1
I used something like these.
Soft enough to not leave a mark on the wood but clamps really good.