1. Steel doors and perhaps window guards of some kind... dont forget about fire escape route though.
2. Read this forum and then view boats to put your knowledge into practise, you will soon figure out the basics and learn all sorts you never knew you needed to know.
5. The first boat I cruised was a 70ft, it is soo much easier than a car and you will figure it out as your go, lots of people single hand. If you are near a canal perhaps put a notice up asking for someone to take you along on a short cruise. Boaters are friendly and Im sure you would find someone. Go and hang around a lock and watch and see how they work, again get chatting and you will likely get to have a go yourself.
6. will happen at some point, again boaters very friendly and if you ask you will get help.
Good luck and dont be nervous