Do the more electrons on the metal in an M-X bond mean a stronger bond?..X can be any ligand.?

Answer 1

In general, no. It's the exact opposite. Especially for first-row transition metals the bonding can be described as purely ionic to a first order approximation, with the metal as the cation. So the LESS electrons on the metal the better.

There are some cases (pi-back-bonding, typically with ligands such as CO and CN-) where the metal can dump electron density back unto a ligand, but in general the fewer electrons on the metal the better the M-X bond is.