Russian signal interception based in central Syria would eliminate the element of surprise from any aerial attack into Iran.
No, if they go they'll be total EMCON and very low.
The Israelis also have other means of delivering what needs doing in Iran, if necessary. Not to worry too much about any Russian radar, though of course the need for coordination is why Bibi and his IDF honchos rushed off to meet with the Russians....to avoid any unnecessary or accidental conflicts given the congestion of different forces (with differing assignments) in such a small area.