I am also interested in this question.
Japan was just at the very beginnings of the fall of the Tokugawa regime. Can I begin the destruction of the Tokugawa regime right from the beginning or do I need to wait some time before doing it? (The reformation into the Imperial system again occurred in 1868, instead of 1861, but the stage was already well set in 1861 for the people to want a change. So I don't know how much backlash, would actually be expected.)
If I were you, I would go for it. Just make sure to find some good RP reason's for it. Get the Meiji Restoration going. Hell, we all know we now need some Imperial Japanese to at least be annoying to Vellos' China.
Will individual people affect the game much? Events that revolve around a certain person dying or enacting certain actions?
Certainly. Historical figures will be one way many factors are taken into account. Military leaders are one example. Another would be political leaders (such as Lincoln or Napoleon II). If Napoleon II dies, then you're going to have to find a good reason for the French Empire to survive and devolve into some revolutionary chaos or power struggles. If Robert E. Lee takes his army to lay siege to D.C., you're going to have to have a good reason if he is to be defeated.
And on another note, those maps are from 1836, not 1861. 1861 is here:
http://en.wikipedia.org/wiki/File:BlankMap-World-1861.png
This is the one I was originally looking at using. Especially since it will be much easier to modify, I think.
