For the stand start (7a) I used a left heel to make the transition in the opening moves easier - it felt like it fit me quite well to do this, I'm 167 cm in height and ape. Then reasonably good holds await until a big move at the top - I rocked over on a high right foot and used a tick mark at the top to add precision as it's quite high above the ground. Very fun climb
Rain sucks, but broken holds suck even more. Remember, never climb on wet rock in Fontainebleau.
The sandstone becomes brittle, and pulling on it will ruin classic problems. Drying it doesn't help, because it's still wet and weak inside.
All you can do is wait for better conditions.