Slitherine

For the "French Infantry Corps d'Armee 1812" I can choose a single cavalry division from the list "French Cavalry Reserve Corps 1812". In this case "The minima for the core cavalry may be ignored".
Does this apply to the core cavalry of the "French Infantry Corps d'Armee 1812" list or the "French Cavalry Reserve Corps 1812" or both?
If this does not apply to the core cavalry of the "French Cavalry Reserve Corps 1812" list may I put heavy and light Cavalry into one division?
I guess I have to, because both heavy and light Cavalry have minima of 8 bases.

The Cavalry corps list still has to follow the rules set out in that list so you can only take heavy OR light cavalry divisions. As you are only allowed one division it must be a heavy division or a light division.

As to the cavalry minima for the Infantry list, it is rather ambiguous. Nothing is stopping you from making a light Cavalry division or 2 mixed divisions or not having any core Cavalry at all!

The entire bullet is discussing the French Cavalry Reserve Corps 1812. Just as the 'ignore all minima' in the bullet above refers to the Guard corps. So you may ignore the minima for the Cavalry corps (since you are just building one division, either light or heavy). You must still also have 4 + 4 light core cavalry from the infantry list.