*shrug*
I'm assuming that almost everyone is going into fate zero having seen/read fate stay night already, so it isn't much of a spoiler there.
Two problems with that. For one, I'm not sure it's a safe assumption; just because they came out in a certain order or it's the most logical or "best" way to do it doesn't mean everyone does. Secondly, there could be people who intend to read/watch them both in the correct order but haven't yet, in which case you'd be spoiling things for the newcomers.
I don't see anticipation as a negative thing. It's kind of to be assumed. If the story had the coolest fights in the early bits, then it would peak to early in that respect. This story is well-written enough that the reader can expect a good build-up to the story climax.
Anticipation in general, yes, but it's kind of rare that something builds perfectly evenly across the whole thing. I'm guessing those interesting things you mentioned don't occur directly after something slightly less awesome and before something more awesome than themselves, for instance.
Also, something I didn't get during the first episode or two of Sengoku Basara (which is all I've seen):
When Oda nabs the guy everyone else was chasing so they could cut his head off, there's this long, dramatic scene where everyone stares in horror as he shoots the guy.
Why?
I mean, they were chasing him explicitly to cut his head off and take it as a trophy, so it can't be his ruthless display of carnage. Were they mortified that he ruined the perfectly good skull with a gun? That he totally stole a noblekill from an army he didn't smash? That they failed in their sacred duties to collect his head personally? That it was Oba Nobunaga and therefore The Bad Guy?
I don't get it.