Fate/Zero

[Xelbair]

I'm not sure anymore

but didn't Saber say she remembers what happened in the previous war because of what she did at the end of it?

or was it because the summoning was incomplete?

It was just Rin's guess about 'uncompleted' summoning(which in fact was perfectly fine).

I haven't watched the Fate/Stay anime, or played... so can I watch this and then watch the fate/stay anime after? will that give me a good understanding of the series throughout, or are there references in this one that I would appreciate if i watch the first series first.

I think it would be cool to watch this and then watch the fate/stay all the way through, but if this is made as a prequel-sequel, with previous knowledge is needed, then I'll watch the fate/stay first.

thanks

I think that you should watch FS/N first, because a lot of things won't get explained.

Have a faint memory of her saying she couldn't be any other classes so checked the typemoon wiki and according to it

Typemoon wikia is very unreliable. Very, very unreliable.