Depends on how SYRIZA acts in government. If it adapts itself to the neoliberal consensus, works with the troika, etc. then of course. I don't support SYRIZA as anything other than a potential force for change in Greece. I have no allusions as to whether or not they'll do what they're campaigning on while in office, especially given the overtures Tsipras has made to the political right in the past few weeks.
Yes and they'd do the same with Sawant, et al of SA if they ever won a national election.
This is definitely not the case, as Sawant is an actual Marxist and SA is a revolutionary socialist organization. The same cannot be said of SYRIZA, which is at best a coalition of left social democrats and some revolutionary socialist groups.