Oh my goodness... your points 1 & 2 struck so close to home!!
I knew I needed a dialogue system so I started from scratch with Brackeys tutorial on a basic dialogue. That got me about 10% of what I wanted to accomplish so I spent 2-3 more days building on it to work for my team's game. That was 2-3 days I didn't have to spent on such a small part of the overall project. I'm happy I had Josh stream my game though where I learned about the Unity asset called Fungus to make dialogue systems easier. Looking at overhauling my game with Fungus now (gross name lol.)
I learned the day before deadline how to export my project to game, but I was stressing until the last minute getting a working webGL build which sadly I never fixed in time.
And here's the link to Fungus if you're still interested in learning it for dialogue system implementation:
https://assetstore.unity.com/packages/templates/systems/fungus-34184