I was in your shoes a few years ago, and still consider myself to be fairly new...but I have figured a few things out...
Make sure you try to keep the weight evenly distributed from side to side, and the secret I've found to tubing is to try to keep the tube out of the wash behind the boat. If you can keep the tube out to the side by turning the boat it'll make for some sweet tubing!
The boat is a blast. I average about 56 with three adult men, about 52 with 3 adult men and 2 women. I've had as many as 7 aboard, but I think it was a little too crowded...JMO
The boats not the best on fuel, but then again it's my first so it's hard for me to compare. I can stay out all day on one tank, but we stop alot and just float around:) About a good hour and a half of tubing will take you down probably 1/4tank...probably
Never been out on anything bigger than a 10,000acre lake...so I can't help you there, and i'm no good at wakeboarding, but it skis fine with 5 people aboard:)
Hope this helps some! ENJOY!!!!

Bruce