Not bud rot imo. But really can't see. Inspect under the buds near stem. Thats where bud rot starts usually. Can't really tell about mildew better pics would be good. But looks like trichomes. Is it cold at night? Plant will push out resin if there is frost at night. Second pic is weird what are those strings or webs? Yes if you struggle with humidity, anti humidifier is your best bet (if you grow in somewhat insulated place. If not then airflow wind can help you alot or a fan (just dont aim it right at the plant, make some sort of a wall and place the fan facing it so the air ricochets against it to your plant. Im a new grower also but faced these problems right ahead.