Well, how do you think I landed 10 ??!!

If you want to take one in, you keep it in the carrier and whisk it off to the vet. Have the tests done: FELV and FIV are the biggies. The vet will check kitty over, give vaccines (since you don't know if any have been done) and then you return home and start the slow introduction process. Snick won't be at risk.

Did this neighbor say why she leaves them outside all the time? Is it a lack of education (she thinks they are fine), or lack of funds?

You do have a problem taking 1 or more in if she says they are hers, though.