You have received a lot of great information from many of the most well-informed, helpful people on this site. The tone of your first few posts brought me back to how I was feeling about a month and a half ago . . . I just want you to know that many of us can very much relate to how you and your whole family feel right now. And having used this forum as one of my most valuable resources, I actually find it hard to believe how much more informed and hopeful (not to mention less scared) I am only a month and a half later :) There is still plenty to be hopeful and optimistic about.
A few comments/lessons I've learned as I've very recently gone through this process with my own dad:
1. Be prepared to wait. From the time that the first test results came back to when my dad got his appts with medical oncologists took a little over a month, which at the time felt like an eternity. This process is very iterative: get results . . . meet with urologist . . . get more tests . . .wait some more . . . get more results . . . And repeat (you get the point). It may take your FIL even longer to get to the point where he is ready to make a decision on treatment, and that's okay too. I'm sure others on here can give you their own time estimates.
2. Make good use of the "waiting" time, but realize that everyone deals with these types of circumstances a little differently. I spent much of the month researching and reading on this forum so that I could pretty much predict / quickly interpret whatever my parents heard at each dr's meeting. This made me feel better personally, but it also, in some ways, overwhelmed my parents. They were just a little slower to process everything, which, now looking back, is okay. Its important to find a good balance between researching treatment information and also providing emotional support to BOTH your MIL and FIL. (i was a little late in realizing just how much my mom was affected by all of this).
3. It sounds like you FIL is already on this page, but if you have to pick one battle in all of this INSIST (or have your husband insist if necessary) that he get a second opinion from an experienced dr in treating prostate cancer. My dad was very comfortable with his local urologist (I actually grew up with his daughter, so they are practically friends). So he was somewhat reluctant to seek out second opinions. At the end of the day, this was the ONLY topic i decided to continue to push on until I got my way. Once the experts took over, I have happily been able to keep my mouth shut.
4. If your MIL or FIL start to feel hopeless (and at times, its okay if they do), find a good resource (email me if you want the one that my parents found helpful) that very CLEARLY shows them just how many drugs / treatements, etc have just recently been approved for use in the fight for pca, and how many others are just on the horizon. This is why there is so much reason to be hopeful. If one treatment doesn't work, there is almost always another one to try, as long as that's what the patient wants to do (I think that is a rough quote from Dr. Snuffy Myers I read somewhere, but i'm not sure . . . just want to give credit where credit is due).
5. And finally, as another forum member recommended to me, make sure that everyone in your FIL's life allows him to make his own decision. I can't begin to imagine exactly how my dad feels about having to choose between two treatments that have equally scary, crummy side effects (that's probably an understatement, which makes my point even more). But I can tell him how much I love him, how much i want him to be around for a LONG time, and how much I will support him regardless of what he ends up deciding to do.
Hopefully these points don' t repeat what others have said. Most of all, do your best to provide support to both your MIL & FIL as they work through all the initiating steps that each guy takes when he first joins this club.
All my best!