Re: Iberian Peninsula
While I agree that the military decisions did occur in Central and Eastern Europe, the Spanish War theatre had still a big impact on that, tieing down some of Frances finest troops (and Allies) - and by that influencing the other theatres of war, like war against Austria in 1809 - most unlikley if the French and Allied main Army would have been in Germany or France.
Napoleon could not afford a war on several fronts and he seeimingly did underestimate this, which is surprising.