"How do I know if I'm filling this in the right way?"
I recommend that you follow our example video at https://elitegamedevelopers.com/convertible-notes-for-gaming-startups/
"Can I used this outisde of Finland?"
I recommend you look at the other templates we provide for the specific country.
"Have you ever done investments with this document?"
Yes! I've done a few angel investments with this document.