What I expect would depend partly on the price and purpose of the class. If the purpose is just to assure the owner that you are competent to operate her brand of longarm safely (meaning that both you and the longarm are safe) then I would expect to learn how to start/stop the machine, how to load a quilt, how to thread the machine, how to oil and clean it, how to change the bobbin, and how to unload the quilt so that it can be re-loaded, assuming that you won't be able to finish the quilt in one session. I would expect that the owner would want to be the one to set the tension and correct it if necessary, but if not then you would need a lesson on that too. These lessons would be sufficient for someone who has prior experience with using a longarm, even of another brand. If someone has no experience on a longarm, then they might also need lessons on using a pantograph (if they intend to use one), or on free motion or even ruler work. It just depends on what they know and don't know, and any additional training would come with an additional price.
How long it takes to do an all over design depends on several factors - the complexity of the design, the density of the design, the skill of the longarmer, the ease of operation of that particular longarm, the throat size (affecting how often you will have to stop and roll the quilt), the type of loading system used (pins, zippers, Red Snappers, etc.), and whether there are any problems encountered (thread breaking or shredding, poor tension, etc.). I would definitely plan on more than one session, partly because you may find it tiring, especially when first starting.
Have fun!