No it doesnt make any difference for Google or SEO aspects - but I prefer to use horizontal navigation bars because the user is familiar with it
I want to use a lot of keywords in it so I wont be able to fit it all in the horizontal one. I want to use up to three phrases (no more than 3 words total) per line...
Yeah it doesnt matter - Google doesnt care if your navigation is vertical or horizontal - with 3 words or 8 words per line ...
Though it is a minor thing but it has great impact on web design, it may make or break the whole design. But I personally like to use vertical navigation. I do not think SE matters it a lot.