I tried Ctrl+F1 to open the dosbox keyboard menu, rebinded as I wanted but it doesn't seem to work (probably because I have a azerty keyboard and dosbox uses qwerty... and yeah I tried to switch to qwerty with Alt+Shift, doesn't do anything). Is there another way to rebind keys ? The current controls make the game even more harder than it already is.

No other way to rebind natively exists. However I've been through both games using my xbox360 controller and joy2key, which actually works wonderfully well for these games. You have to take advantage of joy2key's ability to map more than one key to a single button for it to work, which takes some experimentation. But the game is 100x more playable with a controller. Oh and don't bother with the native controller support.

French or Belgian? Assuming it isn't detecting the proper layout, you may still need to leftalt-leftshift or whatever afterwards.

Yeah, that's what I'm doing too now, the keyboard layout just wasn't comfortable enough for me.