Georg: There are no hard and fast rules regarding the application of warnings and/or penalties. This is one of the things that the TD has to use his/her experience for. As to your question regarding the application of a one hand penalty, if I remember correctly from the last TDA Summit where this rule was adopted, the example used was something along the the lines of a clear rule violation (nothing to do with collusion or cheating in any form) by an obviously inexperienced player. The TD could assess a one hand penalty and during that time, take the player aside and privately explain the rule, etc.
As to penalties being cumulative from one tournament to another, in my experience this is not the norm. However, it would be unrealistic not to expect the TD to be aware of players who constantly 'push the envelope'. For those folks, I think most TD's would forgo the warning and go directly to the penalty. I don't think it matters which rule the player violates, if it is a 'habit' and happens time after time, I think it perfectly fine to start with a penalty.
Hope this helps.