I'm a college student with weak knees. Knees are probably the most delicate and necessary joint in athletic activity. I like to do exercises that mimic those naturally occurring movements you do in real life, such as squats, lunges and step-ups. You can't really strengthen the knee, but you can strengthen all the muscles around it. It not only gives me a good cardio workout, it helps me stretch and tone.
Many hotels have VCRs.
One or two water bottles. I work out for more than an hour at a time, burning a lot of water. I also make sure I have nutritional drinks and at least three glasses of non-fat milk. Some of my favorite snacks, like raisins, rice cakes, fruits and nutritional bars. Keeping a daily journal has been something I've been doing since elementary school.