I am leaving Sunday, July 5, to go to Geneva to stay with friends who are working there for a few months. I'm staying 10 days. We would like to visit Paris for a weekend and possibly even go into Germany for a day trip. Can I still buy rail passes this late and do you need to make reservations? How far in advance? I'm I too late to try to pull this off?

Are you sure you need a rail pass? You might want a Swiss Half Fare card if you are spending most of your time in Switzerland and traveling around a bit. It might be more cost effective. You can buy the Swiss card when you get there. You can read about them on this link to see which would work best for you.
http://www.swisstravelsystem.com/

You don't have time to get a regular rail pass which would need to be mailed, but I don't think you need one anyway. If you want to check and know your itinerary, enter it on www.railsaver.com and click "only if a pass saves me money". I think point-to-point for a Paris or Germany side trip will be your best bet.

We are going to Paris for the weekend and also hope to travel to Germany for a day or two, if possible. The rest of our time will be spent in Switzerland. This will be my first trip to Switzerland. I am staying with friends, but they haven't been there long and really haven't ventured out very much. The husband is working long hours and she is a rather timid traveler. I want to see as many sights and go to as many cities as possible during our 10 day stay. We would have the rail pass delivered to their apartment there in Geneva rather than to the U.S. Would we have time to get one if I order it online today?

If I just get the Swiss Card, then I'll have to buy a pass to travel to Paris. Wouldn't it be cheaper to buy the rail passes for $516 (that's the eurail saver pass since we'll have 3 traveling together) that allows travel to 3 countries, rather than buying individual passes to each destination?

Go to railsaver.com/railsaver.asp and plug in your itinerary. I suspect it will tell you that point-to-point tickets will be cheaper than a pass - and that's without even considering discount tickets that every rail line sells that aren't visible to RailSaver.

"<i>then I'll have to buy a pass to travel to Paris</i>"

Not necessarily. Check out the fares on your potential routes. Many times it is cheaper to just buy point to point tickets and not a pass.

ditto