Getting leather done - any seat cushion recommendations?

So I am getting Katzkin leather installed in my 2012 Prius.

The cloth seats are hard and uncomfortable, so I am hoping that this change will help. Three questions:

1.) What sort of padding is good to ask them to install? Is memory foam the most comfortable and supportive?

2.) I already have heated seats from the factory. Will I lose this or can they be carried over?

3.) I have the normal dark grey cloth seats/interior. What Katzkin leather name exactly matches this interior or the Toyota factory leather color?