Hi, y'all!
Alison, welcome to the wonderful and sometimes frustrating world of fiddling.
I think your search of the forum would turn up lots of suggestions about the ways to set up your fiddle--- including the choice of shoulder rests, and strings and other important info. I don't recall anything about bows though.
You can get decent bows for less than a $100 US and if I were you I would look for the following:
1)wood rather than fiberglass, the tone is more pleasant
2)horsehair rather than synthetic, because the tone is more pleasant
3}with some tension on the bow, sight down the stick to see if there is too much warp--- which could make the bow difficult to use.
About bow weight---it is a matter of preference. I have one heavier and one lighter, and I use them depending on the mood I'm in. You can adjust the bow weight by visiting your local fly-fishing supply store where you can buy some weighted floss for tying flies (it makes them sink) and you can wrap that around the stick to adjust the weight of the bow.
Finally, there is a right way and a wrong way to hold the bow, and I would suggest that you have someone show you how so that you don't get into a bad, bad habit that is difficult to unlearn later. And since you are starting out, maybe they could show you how to tape the neck to make it easier to learn the fingering.
Get a better set of strings and don't bow too close to the bridge unless you like the sound of bats having sex! :)
I'm sure that there is always a better bow out there. If you take care of it the bow doesn't wear out--- you can generally find someone who can rehair them.
Happy fiddling!
Hardi