No, I think that's exactly right. That's why I look at the 1" and larger figure.
I don't know what mil you have, so I can't advise whether you would have use for a bigger end mill. Which model is it?
RE number of degrees of positive rake, that's going to be very application specific. You can get the rake from either the way the insert is mounted or the insert itself. Very often it is a combination.
I'd ask the seller to point you to the manufacturer's web page for the end mill. Take a look there and just see if positive rake is mentioned. For example, here is the Lovejoy facemill page I mentioned:
http://www.lovejoytool.com/f225.htm
It mentions both the positive rake and goes on to say, "ideal for small and light duty machines in general purpose applications." That's us home guys! Most of the manufacturers will make such a mention.
Your 12L14 leaded steel should be very easy to machine, BTW. You won't need the last word in cutter technology to do it. Nevertheless, eventually you'll want to cut something else.
And I would definitely not discourage carbide on these small machines. It works great.
Best,
BW