I prefer using notepad++ for my modding. It recognizes and highlights python syntax, allows me to open lots of files in the same session, and even has a simple file compare feature. But esentially, even notepad will do if you don't intend to do complex modding.
For the time, you must decide for yourself what you think as comfortable but still challenging enough. As it is coded in CE, the timer is scheduled once every half minute. So the 7+pc.stamina means, you loose blood every 4 minutes if you have stamina 1, 5 at stamina 3, and 6 minutes at stamina 5.
I'd suggest you try for 5 minutes at stamina 1, plus a minute for each further point of stamina. That would be 8+2*pc.stamina.
Give it a try and find out what suits you the best. Making changes to python will not cause problems with your save files. Just be careful about indentation when you edit python scripts. Due to the simple structure, this language is a bitch for indentation.
Tuesday is Soylent Green day.