The anti Zionist stance is simple: Currently israel can accept a two state solution as offered by the Palestinians. Even Hamas is offering this. If israel accepts it israel loses their status as Nazi terror colonizers and gains the right to exist.

But because israel is Nazi-like state that wants to keep expending their Lebensraum far beyond Palestine into Lebanon, Jordan, Egypt, Syria and even as far as Turkey in the future, israel will not accept this. It's like asking if Hitler could just divide the land

Now for your other question, Hamas is a resistance movement not the government of the state of Palestine. If the state of Palestine is re established it can hold elections and Hamas will be a candidate in the political race.