Thanks. 1 GB isn't too bad. It's the full game, when it comes out, that I'm worried about if I have to download it.
As far as the full game (retail) goes you can order the box (add in S+H) if you're concerned it'll be too much for your connection. From my understanding you can also DD using the box set order too -- best of both worlds. Check out Pre-Order
where it mentions Download + Retail Box plus S&H, and DD only.
Regarding beta, I don't know of any way to get it other than impulse.
There is a possibility you may want to check out (scroll down to the "Copy Protection:" part): "Users who do not have good internet access at home can use http://anywhere.impulsedriven.com to download Elemental and bring it home to install on their machines."
Not sure if you have a good alternative connection (work/friend/etc.) or if it'd work for beta, but should work for release so you wouldn't need get the boxed set, or wait for it to arrive if your connection is insufficient.