Paladin Geological Services interview questions

I was called on a Friday for a 15 minute phone interview and then asked to do a video interview the following Monday for 30 minutes. It was a fairly basic interview. One thing I noticed is that they didn't really ask me a lot of questions. It seemed like they did a lot of telling me about the job itself though. In the past, this has been an indication that companies just want a body to fill the position. You're expected to drive your own vehicle to the drilling sites but sounded like you would be reimbursed for gas mileage for up to $300 per well. They said that it worked out to about 26 cents per mile which is odd because I thought federal guidelines made it to where you should be reimbursed at 53.5 cents per mile. You're also given a per diem of $61/day. Maybe the per diem is supposed to make up for the milage??? I'm not sure what the hourly or daily pay rate would be for this job. That is one question I did not feel comfortable asking. I was told that if I was working out of Oklahoma that work would be two weeks on and one week off. For south Texas it would be four weeks on and one week off. I thought my interview went well. I asked what the next steps would be and was told they would be putting together an offer letter to get me into their training program in early to mid May. Maybe I'm impatient or misunderstood, but I have not yet received the offer letter that we discussed in my video interview. I was also told that once I received my offer letter that I needed to put in my two week notice to my current job immediately.