Started bouldering and I have a few questions

Backstory: got interested in bouldering through YouTube and I've been watching a lot of videos to help me improve. I've been climbing three times now and I started this month and it's safe to say I'm having a great time doing it. The community is very welcoming. I don't plan on competing but it would be nice to one day not be limited to what routes I climb and I always enjoy a challenge and pushing myself. I'm able to climb my gyms V1s and some of the V2s and my very first V3 today.

The questions: Why are some V2s harder than V3s and why are some V3s easier than V2s?

As a beginner I have a hard time with some of the smaller hold so what would be the best way to improve my grip on those holds?

Sorta like question 2 how can I improve my finger strength? I've tried the hang board with assistance and it seems impossible even when my feet are still on the ground.

Last are there any good reputable youtube videos or channels that are good for beginners to watch to learn techniques and the ins and outs of bouldering?

Please don't beat me up in the comments I know I'm extremely new but I wanna improve and start a training regiment to help me. Thank you!