steering reservoir

[Shamrock]

Sorry guys,
I am going to drive you nuts with questions that may seem silly, but I am a noobie to this car.
1. The liquid in my steering reservoir when cold is halfway between the cold max and minimum line. Should I top it up or is this preferable?
2. I am not used to such a low steering rotation (1.5 turns)and I end up always turning to lock. Does this cause damage? Should it be avoided? My last car (audi S3) had electric steering and my first car was an alfa 164 that blew the steering line when I turned to full lock.
3. How the h*ll do you get the cap off the reservoir. It doesn't have threads so I just pulled it off and then snapped it on. Is this o.k.? Why no threads?

Thanks