2) Yes they did. Why else would they have helped law down the foundations of the Israeli state and immediately recognised its existance. As opposed to offering similar assistance to the Palestinians. They didn't just leave, they had a plan of what they wanted the state to be.
Actually no, Empror Mike is quite correct. The Balfour Declaration was issued not because the British had some great desire for an independent Jewish state but because they thought calling for it would encourage American Jewish to pressure America into getting involved in WWI and encourage Russian Jews to pressure their own government to not back out.
By 1921 according to almost all historians who've studied the situation, such as Paul Johnson and Connor Cruise O'Brien, the British Foreign Service had turned against the idea of creating a Jewish state and even most British politician who supported Zionism did so reluctantly and only because they didn't want to break their word any more than they had to. From then on, untill the British withdrew in 1948 there were constant conflicts between the Jewish immigrants and the British administrators.
Also, with all due respect, your claim that the British "lay down the foundations of the Israeli State" but offered no "similar assistance to the Palestinians" shows gross ignorance about the history of the founding of Israel.
In 1922 the British decided to split off 80% of Palestine and made it into Transjordan. The few Jews in the area that became Transjordan were "encouraged" to leave and laws were passed with the approval of the British making it illegal for Jews to buy land or move into Transjordan. Such laws are still on the books in present-day Jordan. It's also worth noting that I think King Abdullah himself would be surprised at the suggestion that he and his country recieved less assistance than the Palestinian Jews much less "no support." The soldiers in the Arab Legion and their commander with the distinctly Arab name, John Glubb, would probably be equally surprised.
Even if you want to pretend that Transjordan/Jordan was never part of Palestine suggesting that the British never attempted to lay down the foundation for an Arab state within present day Israel is asinine. Read the Peel Commision report of 1937. The British recommending dividing the remaining 20% of Palestine into an Arab State and a Jewish State with the Arab State being roughly twice the size of the Jewish State. The Zionist leadership was bitter and divided but were willing to accept it. The Arab leadership rejected it out of hand.
I'm also confused by your statement that the British "immediately recognized" Israel's existance. Eventually, Britain decided to wash her hands of the Palestinian mandate and left the decision on what to do with it up to the UN. The UN decided to divide the mandate into two states of roughly equal size, one for the Arabs and one for the Jews. The British abstained. Now, yes, they did recognize Israel's existance following the UN vote, but so did just about every non-Arab government on earth.
Oh, and since you said the British had "a plan on what they wanted the state to be" you should note that the UN gave the Jews a much bigger state and the Arabs a much smaller state than the British offered in 1937.
I have to say I think Bevin might be a little surprised by your suggestion that he was a philosemite.