I'm sorry that your family is going through such a tough time! You are a good daughter, and speaking as a parent I know that your parents deeply appreciate your support. Continuing to speak as a parent, I'm pretty sure that the #1 thing you can do for your parents' peace of mind right now is graduate! So put that up there on your priority list and get it done, even if it isn't perfect.
Regarding the lung nodule: at least 60% of the lung nodules detected by CT scans are not cancer, especially if they are small. Your father's oncologist is doing the right thing: they will keep an eye on it in future scans, and take steps when and if necessary.
I think you father has the right attitude. I made a personal vow when I was diagnosed but hadn't received the pathology report that I wasn't going to freak out about anything until I knew I had a reason to freak out. This didn't stop me from becoming informed, and in fact the more informed I became, the less inclined to freak out I was (and am).
It is very unfortunate that your father has people around him who fall for all of the unscientific crap out there and try to frighten him away from chemo. Another thing you can do for him is tell them straight out that he is making decisions informed by evidence-based medical science, and that while you appreciate their good wishes, they should keep their opinions regarding treatment to themselves because it is NOT helpful to him. With some people there is no point in being diplomatic. They will not take the hint. Just tell them straight out, but kindly and politely, even if it means calling them or emailing them on your own. I personally have been very lucky that I was only approached by one person peddling essential oils, but others are plagued by friends and family and I know it can be very dispiriting.
Do you know WHY your father's onc recommends this course of treatment vs FOLFOX? I'm sure there are good reasons, but it is important to understand. The positive would probably be that he doesn't need to be on the pump for 48 hours. The negative may be that more people seem to suffer from hand/foot syndrome on Xeloda. It is important to keep ahead of that, if it happens to him, with effective moisturizing. (I've found that Aquafor is particularly great for the feet, but I don't have H/F. Those who have dealt with it can help you out.)