Has anyone gone to an immersion school?

[RZM]

3. I've done it a few times

For Russian. Two different summer programs in the US and one at Moscow International University. During the latter I lived with a host family that spoke no English at all. That was pretty challenging and awkward at first, but I eventually got the hang of it.

I wouldn't expect to get fluent in a month, although Spanish isn't particularly hard. But look at it as a long haul. In any case, a few months of immersion will do you well, even if it won't get you all the way there. I say go for it.