It's up to you to feed live or not. I feed mostly live. I'm not going to debate it with anyone, btw.
He could be small because of poor husbandry, and might pick right up once he's in a good environment. Quarentine is paramount. If it's a snake from a rescue, then the original people probably just bought it at a Petco or something. That would mean 90% probabilty male. I think most of the balls sold in the big petstores are probably males, since there is slightly more demand elsewhere for females, but it's all guessing on my part.
If you want to get it, you have the enclosure for it, seperate and quarentined from your currant animal, and you are willing to at least start out possibly feeding live to it, then I'd say go for it. You might train him over without ANY issue, if he's got proper heat, humidity, and no stress. He might also just plain remain a live feeder. Who knows.
I guess it's not all that helpful. Sorry.