A Republican victory and World War II

[Snowstalker Mk. II]

Speaking of the Spanish Civil War, of course. All I've read about the war suggests that, due to German air support and a lack of unity among the Republican forces (the socialists, communists,  anarchists, and liberals all hated each other), the Falangists had a natural advantage in the war. Therefore, I have a few questions:

1. How can the Republicans either win the war outright or at least delay Franco's victory?

2. Assuming WWII goes as it did in reality, does Hitler invade Spain after the fall of France?

3. If he does, Spain is surely very weak but has the advantage of being tough terrain to invade. How long do they last; or could it turn into a longer land war between Britain/Spain and Germany?

4. Would this delay Barbarossa?

EDIT: Move this to Alternate History.

[Snowstalker Mk. II]

I don't think France would help directly for the reasons you mentioned, but I suspect, now that I think of it, that Hitler would certainly invade Spain after June 25th; it was left-wing, easy to conquer, and at the bottom was the real prize: Gibraltar.