First, let me suggest the following book, available from Amazon or other
sources:
Managing 12v Volts, How To Upgrade, Operate & Trouble Shoot 12 Volt
Electrical Systems by Barre
An Internet search should find somewhere a good explanation of the
relationships between voltage, current, resistance and watts (or power).  A
basic understanding is needed to define your needs.  And it's not really
complicated once it's explained.

Second,  I think you will find that the electrical consumption of any one,
let alone all, of the cooking appliances you list is well beyond the
capabilities of any solar system practical in a Vanagon.