If only a tiny amount of water has fallen onto the carpet, the water may not penetrate the deeper layers of the caper and won’t reach the foam underpadding.
No, not if the water is cleaned within 48 hours. If the water is clean, it won’t contain many contaminants and thus won’t introduce much bacteria to the carpet.
Use a dry cloth or towel and blot the area. Press the cloth/towel into the carpet with enough pressure to soak up the water seeping deeper into the carpet.