how long is the trip from the center of Beijing to Simatai? Where do I get combo tickets in Beijing?

I will be in Beijing on the 28 of August.
I'm looking for informations on the trip from Beijing to Simatai with buses, because I would like to reach the base of the wall as soon as possible so I have the time to walk up the wall as much as I can.

First of all, it is okay to hike alone or I will need to have a guide?
Can I hike also after Tower no.10 or is it forbidden? which kind of equipment is needed? and after that, do I have to walk all the way back to Tower no.2 or there is another way to leave the wall?

Also, if I want to hike at least until I reach Tower no.10, will I also have time to visit the Water Town in a day? IF so, where can I get tickets in Beijing the day after, so that I won't need to make reservations (I will also have difficulties because I don't speak/read Chinese)?