You are doing the exact same move I did almost a year ago, but I bought the 20mm pancake lens.
I wanted zoom all the way, all my life I shot with a zoom lens so it was my wish to acquire the GF1 with the 14-42. But some friends kept telling me how the 20mm was awesome and forget the zoom, so since I was making a move to a more serious gear, I took sometime to read, read, read and look at samples from the 20mm, in the end I bought it.
What has been my problem since? Shooting wild life! Does it really matters, not that much, seriously, spending some good money just to have the ability to shoot some birds it's simply not worth it. After almost a year of using a prime lens, I am extremely happy with it, it's fast, it takes awesome pics, and it's very portable, if I am not planning to go out and take some photo gear, I can just take the camera with the lens. Sometimes do I wish I had that zoom? Yes, but seriously, it's not that big of a deal. I can work it out, walk a bit further or back.
As to the mater of talking about a zoom lens, well to the realm of Panasonic lens you are right the gap is huge, the 12-35 f/2.8, besides new, has a higher build quality, which makes its very pricey, the same lens with the build quality of the old 14-42 would be a nice addition for those with not so deep pockets. So your solutions pass through looking at Olympus lens (thing that I actually never did so I can't give you any insight), or work with your prime. If you worry about shooting indoors, why do you need a zoom lens?
Image stabilization, well this really varies from user to user since a person might be more shaky than another but since the GF1 has no viewfinder one typically shots only with two hands holding the camera and there is no 3rd point to hold the camera (usually face), this brings less stability, so it helps, but since I have no zoom lens I can't give a real input on this subject. I don't think you need an adaptor there are a lot of lenses for m43.
So answering to your title question? Don't get, use the 14mm prime lens and work your creativity out, if you really really need the zoom, attach the 14-42 and shoot!
p.s.- nice pics :P