Is a person considered negligent if he ignores the severe whisperings (waswas) that afflict him during acts of worship, such as prayer, fasting, intention, and so forth, which push him to constantly seek out jurisprudential rulings, all in order to resist these whisperings?

You must ignore these whisperings (waswas) and turn away from them, for indulging in them leads to great evil. If you have ascertained the factors necessitating apostasy and the conditions for mockery that constitutes disbelief, then do not pay attention to any whisperings that contradict this. The description of prayer, with its obligatory acts, conditions, and pillars, is clear and easy, and you can consult concise texts regarding them. If you have ascertained these rulings, then do not pay attention to any whisperings that arise. Neglecting the Sunnah acts of prayer or being deficient in them does not affect its validity. Turn away from the whisperings and do not give them any attention until Allah removes them from you.