I just recently switched to vim full time, maybe 4 months ago, after my existing IDE switched to a subscription model following two updates that made the software more and more buggy. I don't have definitive answers, just experiences:
1. The first two weeks were hell. It felt like learning to use a keyboard all over again. I've tried to get started with vim multiple times, leaving because I needed something faster. This time, I just happened to catch a break in work where there was no one breathing down my neck to get stuff out the door yesterday.
After two weeks or so, you start to learn the vim mindset. It's hard to explain, but vim is both a language (via movements and interacting) and a way of thinking (via modes). I'm still adjusting to all of those, but it's gotten to the point where I think of a task, attempt it with the shortcuts I know (the "language"), and 2/3 of the time, it just works.
2. Is there speed over previous IDEs and text editors? It's about the same for me, with the added benefit that I'm no longer tied to a system I have to pay for, it's cross-platform, and pretty available in most sports.
For Mac at least, there are things like MacVIM where I believe they let you use your mouse to click around. I did all of my learning from the Laracasts vim series, and I really like his approach of doing what works for you. MacVIM adds shortcuts like command-S to save instead of :w and stuff. If it works for you, cool. I took the approach that I want to learn the base system (plus plugins) because that is a more common cross-platform interface.
From using an IDE, I don't know if I'm saving time by not using the mouse or not, but I know that I can more quickly get places within the code if I know where I'm going. I assume the benefit of not reaching over to use the mouse is helping, but I can't really tell.
For me, there were other reasons, but I don't regret the switch at all. I'm still quite the novice, but I've switched to using it nearly exclusively for projects. (If I just need to quickly open a file from the Mac Finder, I double-click and something non-vim opens. I'm OK with that, I'm no purist.)
The only place it bites you is when you use vim for a while and then go back to something like Code or SublimeText and you're typing vim commands into the screen as characters. Make sure you double-check your work so that you're not pushing ":w"'s up to production. :)