1. Many don't require biochem. It may be a good idea to have some anatomy as it will at least expose you to it. Anatomy in PT school can be overwhelming so it can only help you. So I think anatomy is a must, biochem is not.
2. I think you should shadow as much as possible. Remember, to apply to PT school, you need a PT as a reference so the more you are with them, the better reference they can be. There is a minimum number of hours required by each school but remember, it is the minimum. I think by the time I applied to PT school, I had 7000+ hours (I was a full time aide for a few years). You definitely don't need that much but you should do more than the minimum required. Just my opinion.
3. I've seen people apply to tons of schools (the PTCAs has made applying much more accessible). I guess this gives you options if you get accepted to them. Back in 2003, I applied to 3 and deferred them all to take time off from school for the time being. In 2005, I applied to 2. If you are thinking of applying to PT school, apply to those that you are interested in whether 2, 5, or 10 schools. (Just keep in mind that applying is not cheap). I think with the PTCAs, it may even be harder to get in now as there are probably more applicants for just 20-50 spots.