1 - It's not written in stone. What I do is run a 6-8 week cycle and then take a week to max out on the three main lifts. After that week, I take a deload.
2 - This kind of ties into your first question. I switch exercises every 2 weeks. I try to beat my mark from the first week in the second week. i.e. - If I pick close-grip bench for a ME exercise, then I would do 225x3 one week. Then the next week, I would try and beat it for weight or reps. The next week, pick a different exercise.
3 - Never experienced this. I just pick a weight and stick with it for 3-4 sets and do the prescribed reps.
Hope this helps!