And what questions should I ask the landlady when finalizing this deal?

And, oh my fucking God, I just bought the latest Cornelius album, and it's blowing my fucking mind. But that's unrelated.

Sounds like a great deal! Especially if you can sublet your extra two bedrooms between now and September- make a little extra cash on the side ;-)

I'd try and get her to cover the cost of movers, since she's asking you to move early.

May not work if you've already said you, too, want to break the lease instead of finding another roommate.

Kellydamnit, I don't think mulp originally wanted to move, it's just that the landlord is jumping on the opportunity to empty the apartment.

Mulp, I'd say take it, since you were planning on moving in September anyway. And TPS has a great suggestion - lease one or both of the other bedrooms and make a little extra on the deal. Just get it all in writing.

... and mulp, you already know one young lady who is probably looking for a room.

Wait ... mischief, I do?

Hmmmm. Although you were thinking of moving out in September anyway, this would mean moving in a month and then probably moving again three months later or so. What are your rights as a tenant where you live? Can she or the new owners simply evict you when your lease ends, or do they still have to show cause? I'd also take a look at the apartment (though you've probably already thought of this), not least because in my experience a landlord's definition of 'bedroom' can be quite broad, unlike the room they're describing. If it all looks good and you're not going to get stuck with two moves in the next few months (or if that prospect doesn't bother you), then sure, go for it. I second kellydamnit in pushing the l/l to pay for or at least help generously with moving expenses, though. You're doing her a favour after all, and you shouldn't have to pay for that.

Also, many congrats on soon being rid of the kitty-neglecting couch-pissing blight of a roommate.