1. If you care about your spelling, you just need to find the right layout (which would be "English (international AltGr dead keys)" on Debian), then it's almost as easy as the azerty keyboard:
é : altgr + e
` : altgr + ` (then the letter)
¨ : shift + altgr + ' (then the letter)
^ : altgr + 6 (then the letter)
If I remember correctly it's slightly easier to type é and è on an azerty keyboard, but not that much.
2. vim is qwerty centric, the best example for me was using CTRL-[ instead of ESC which actually makes sense on a qwerty but not on an azerty. It doesn't take that much time to learn new habits.
Overall, I would advise against changing your layout unless there's another good reason. I decided to switch because I was using many computers with a qwerty layout, and only my personal computer was still with an azerty layout. It sounded more productive to just have one layout instead of having to think about it.
Well, I guess it's a matter of preference, then, because I definitely feel like having to press 3 keys instead of one is indeed a problem when you have to do it four or five times per sentence :)
A side note, btw, regarding CTRL-[ : it seems not to be well known, and it doesn't work on things that use "alt" to access file menu (like gvim), but using alt + <normal mode key> in insert mode instantly drops to normal mode and execute that key. For example, I usually leave insert mode by doing A-j or A-h, I never hit the ESC key.
My favorite trick is `A-e a` when inside parenthesis to jump just after it and still be in insert mode, like when writing parameters to a function and jumping out of parameters list to add the `{` character.
If I remember correctly it's slightly easier to type é and è on an azerty keyboard, but not that much.
2. vim is qwerty centric, the best example for me was using CTRL-[ instead of ESC which actually makes sense on a qwerty but not on an azerty. It doesn't take that much time to learn new habits.
Overall, I would advise against changing your layout unless there's another good reason. I decided to switch because I was using many computers with a qwerty layout, and only my personal computer was still with an azerty layout. It sounded more productive to just have one layout instead of having to think about it.