Hello there Zinzin!!
Well, since you really did not ask any questions, I'll just start by responding to some things you stated!
Ok, you say that you will mostly be doing B&W... does this mean that you will also be doing some color?? If this is true and you will be doing primarily B&W, but also color, you will need an enlarger with color head. It has a "box" on the top and allows you to 'dial in' color settings. You can also use those color settings like filters when you are enlarging B&W. So an enlarger with a color head can do both, while an enlarger that does not have that head can only do b&W.

Most enlargers will work for at least 35mm and 120mm. You may need different lenses for each size...I do for mine. I have an older Beseler 23C II which is a wonderful machine. I only do B&W. I have a 50mm lens for 35mm enlargements and a 75mm lens for my 120mm enlargements.

I don't know if any of this is helpful, but it gave me a chance to limber up my fingers this morning!