1.  Probably not.
2.  Probably not, considered very poor taste, and would likely result in her showing him the door very fast.
3.  Not that I know of, unless it has visible manifestations.

I can't really tell from your handle whether you are a potential provider or hobbyist.  I would guess provider.  STD's are always a concern, which is why the vast majority of providers only perform covered FS, and many only do CBJ as well.  If you are a hobbyist, you are better off with well-reviewed providers than a civvie chick you picked up in a bar, esp if she is providing full time as her only source of income.  She will not jeopardize her livelihood by not staying disease free.  If you are considering providing, you just get yourself tested on a regular basis, and use appropriate safety measures.

Swim

If you read the threads on this, which you should, you'll understand that there is no ironclad way to be sure you won't get an STD of some kind, except for celibacy. The same is true from civvie sex.