Hello, I usually praise myself for being technical minded and have successfully solved most of my MTB problems but I cant for the love of god understand BBs.
I'm looking for a new crankset for my Ghost SE 1800 (2012) but I cant find out what kind of BB I need.
The bike actually has an Octalink V2 cranks and a BB ES25. Now my plan is to get smth fancier like a hollowtech 2 system.

Now on a little research I did I found BB ES25 comes in different sizes. There are some numbers that show different versions but I cant figure out what they mean.

So my first question is how do I figure out which one do I have without removing the BB as I dont have the tools to do so. (I couldn't find it even in the bike manual as it only wrote: bottom bracket - BB ES25
My second question is how do I look for another BB that fits my frame. (Ill most likely look for it online as I felt prices on my local shops were a bit salty)
I don't know if this is relevant but I've converted my bike in a 1x9 setup with a narrow/wide chainring.
Thank you!