Is intense fear of God and scrutinizing the minutest details of what is lawful and unlawful considered to be waswasah (insinuating thoughts), or is it what is Islamically required?

Piety (taqwa) leads its possessor to be cautious in matters of their religion and to avoid doubtful things, which is the praiseworthy scrupulousness (wara'). As for blameworthy rigidity (tashaddud), it involves prohibiting what is lawful, or abandoning it as an act of worship, or worshipping with what is not an act of worship, or exaggerating in worship to an unbearable degree. It can also manifest as obsessive thoughts (waswasah) that drive one to excessive meticulousness, artificiality, and undue hardship. The Prophet, peace and blessings be upon him, condemned those who were excessively meticulous. Indeed, the religion of Islam is ease, and it removes hardship.