It was good to take today off . Every few weeks, I think I said 12 but that could be wrong (old age) you want to take either a few days or a week off. That gives your body time to rest and you can go into your full routine with as much energy as possible.

On to your questions: 1) yes you can do Treadmill on the days you are there. Depending on your goals though, if you are looking to gain mass/muscle then only 1-2 days of treadmill because you want to keep as many calories as possible. if you are looking to lose weight and fat then 4-5 days of treadmill (doing treadmill for 5 days is okay as long as its not weight training 5 days) I would also see how treadmill fits into your leg exercises, you will have to decide whether to do it first or last depending on how well your exercises go.

2) when I said everyday training I meant the Mr. Olympia everyday training, those guys go ALL OUT before a major competition and what happens is your body creates enough energy to fuel you for those 7 days (although as I've said you increase risk of injury) your body does not just "shut off" when you decide to go down to 4 days. You will still have all of that excess energy so depending on how long the competition is (if its a week long that might be enough of a break to go back to 4 days) if its only a weekend competition then they will go to a 6 or 5 day split to allow their body time to readjust.

Now when you get your training schedule together (exercises you are going to do) you might want to switch those up during your 12 week cycle. Read back about what I said about muscle memory, if you keep doing bench press, declined barbell pres and then inclined fly's your body will adapt. You might want to do fly's first so that your body doesn't know and can't adjust to which way you are training them.

Overtraining is very serious, it is always better to start off slow and then increase to say a 6 day split after a few months if your body can handle it. If you've ever been bowling before you know the ball has a thumb hole (sorry I was into bowling as well ) so we had a saying when drilling those holes "you can always take more out, you can't put back in" It's sort of the same thing, you can INCREASE your workload as your body tells you but you can't necessarily decrease because the only way to know you have to decrease is usually an injury and that's no fun.

I'm sure there is more I could say (could you tell?) but if you have any questions just post them here.