Syriza is indeed Leftist, with 'nigh-communist/radical left' being a more apropos descriptor. It even has a Maoist component, which is quite an interesting thing for a Western country in the Twenty-first Century. As for it being against the EU(SSR), it is simply because it is a far-left party that is anti-establishment, and that they have used anti-austerity as a populist mechanism to get the support of the people (and the Greek people have a lot to complain about, which worked well for Syriza).
Syriza is nowhere close to Conservative - at least what is considered conservative in the US.
Exactly, and Independent Greeks allying with these comies is vile