Company forewarned drug testing will be done on-site @ interview

What type of testing do companies do on site?
I have an interview scheduled in Atlanta, GA. The hiring manager gave me notice while I am at the corporate office I will be tested there on-site. I am driving back and forth from the airport with her since she is meeting me from the Dallas region. I would die if I failed a test and had to sit in the car and ride all the way back with her. Besides that, I have a recruiter working for me that has already lined up 3 great interviews. I can't afford to blow it.

1- I only smoked 2-hits, three consecutive nights about a week ago. Last time was Friday, Dec. 4. The interview is on the 18th.

2- I am a pretty petite girl, 5/1, 118 lbs. and did not smoke for months prior to that.

3- What kind of testing should I be prepared for? I had never even heard of employers testing on-site! I have always been sent to a clinic for a urinalysis. WTF?

4- Today, I passed a home urine test. Does this mean I may pass a hair test or saliva test as well if that is what they administer? Are there any other type of tests?

5- I am doing the exercise and niacin as noted on other posts as a preventative measure.

Any help is appreciated.

It should just be the regular old strip test just like you used.
1: Sounds like you should be fine. Eat a high fiber diet with metamucil and exercise. 3 days before UA switch to a red meat, high fat diet and stop exercising. Morning of the UA follow the dillution sticky.
4: Blood test is only good for 3 or 4 days so you would pass that easily,hair test is for 3 months or more. You might pass that with your small amount of smoking but its iffy.
If you passed a dip test you will be fine by UA day. Just follow the directions above for added insurance.