You can climb a rock without leaving any trace whatsoever on the rock. This is called clean climbing and learning to lead is your first step towards it. Having clean shoes is often more important than having the 'right' brand of rubber. Bouldering on a sunny, dry and cold winter day can be an excellent experience. Here are some tips for winter bouldering.
Dehydration is a major source of performance decrease while climbing.
Learn to avoid it by making your own electrolyte sport drink. Slacklining or walking a tightrope is certainly one of the best ways. Learn it here. Tom Cruise insisted on doing the climbing scenes in MI2 himself. Meet activity partners for Climbing and dozen other sports.