How can an entire room be purified from defilement without damaging the wood with water, and does a damp wipe purify when wiping away defilement? And what about purifying the body after entering the restroom and being contaminated with urine and feces?

Do not rule something impure unless you have absolute certainty. The default state is purity. Overriding probability is sufficient for the removal of impurity when performing istinja (cleansing after defecation or urination). A room that has become impure does not need to be purified unless one intends to pray in it, and it suffices to spread a pure rug over it. To purify an impurity, pour water over it, or wipe the impure spot, and do not pay attention to whispers [of doubt].