hi I’ve recently remodeled my dining chairs to make the backs shorter.

I haven’t stretched/ re-attached the leather yet as l need to finish off the legs. I sanded them back and would like to know which product is best to use to stain / finish off the timber.
I’ve also heard it’s possible to recolour leather and a contemplating trying this if anyone has any advice regarding products/methods would be appreciated. Thanks ☺️