Q) How do I know how much weight to use?
A) There will be a column on your program titled "Effort" and each set will be assigned either Light, Medium, or Hard. If it is Light then you should be able to complete the proscribed number of reps pretty easily and without any significant strain. So pick your weight accordingly. For Medium, it should be difficult to complete the proscribed number of reps but you should not feel like you're going to failure. For sets assigned Hard, you should either go to failure or within one rep of failure.
Q) What type of cardio should I be doing?
A) You can do what ever type of cardio you prefer. Although, stair steppers and inclined treadmills are generally considered superior methods of cardio as they recruit more muscle.
Q) Can I still workout if I'm sore and the program calls for me to?
A) In most cases yes, but if you are still very sore then you should wait until you aren't before resuming the program. If you are just slightly sore make sure you thoroughly warm up. It's very important to listen to your body, if you are too sore it's perfectly fine to move everything back a day or two.
Q) Can I workout more often than the program calls for?
A) Yes, generally speaking, increasing the frequency you train a muscle the faster you will progress. In most cases, though, if you find you have too many rest days you likely either aren't pushing yourself hard enough or you need the next step up in difficulty for your program.
Q) What if I don't have the equipment to do certain exercises?
A) That is perfectly fine. Simply find an exercise that is as similar as possible to replace it with.
Q) How long should I follow the same program?
A) If you find that the program seems too easy then simply request another program and increase your experience level and or intensity in order to get a more difficult program.
As far as feeling the need have more variety in your workouts, that is not really something you need to worry about. If you do want to mix things up you can always just pick an exercises or two every workout to replace with something different that works the same muscle group.
Q) Where can I find the video tutorials for the exercises?