Help with map projections

[Soixante]

Dear smart people,

I need some help with the following: I have a map of a continent, like so:



Please note, this is just an example, the real map is still a work in progress.

The area covered by this map corresponds to the following area on a map of the whole world:



Roughly, this is between longitudes 23° W to 28° E, and latitudes 43° N to 4° N. Now what I want to do is to make small, regional maps from the map of the continent. Sort of like this (again, just an example):



However, I want to be able to change map projections when going from the continental map to the small regional maps. I also want to be able to add an exact graticule of meridians and parallells; it needs to be correct with the projection used and I want to be able to have a very fine graticule down to single degrees at the very last (preferably minutes).

I have FT3, but the problem is I cannot seem to import a pre-existing shape/continent as a black and white image and then specify the latitude and longitude limits of the map, the projection I want to use, etc. If FT3 allows this I am not able to figure it out. I have also looked at some plugins for PS that allow to change the projection of an image, but of course then it's a destructive way of editing and they are not really suited for my needs, I think. I have also looked at G.Projector, a free software that was made specifically for changing projections, but I am not sure that it, either, can do what I want.

I would really appreciate some advice and recommendations for which software could help me accomplish what I want to do.