WASHINGTON - Republicans looking at Rudolph Giuliani's campaign for president always ask two questions - is he really running, and is he a "real Republican?" They're probably not going to like the answers found by Newsday in Giuliani's government filings. The ex-mayor still is holding back from submitting the simple one-page form declaring himself a possible candidate, despite raising $1.4 million to run. And asked what party he belongs to on a different form, Giuliani didn't say - he left the answer blank.