Is stopping at the verse: "And ask Allah of His bounty" in Surat An-Nisa, and supplicating thereafter, considered an innovation (bid'ah)?

There is no harm for the reciter to ask Allah when passing by a verse that encourages supplication. It is recommended for the reciter, both inside and outside of prayer—whether as an imam, a follower, or praying alone—when passing by a verse of mercy, to ask Allah for mercy; or by a verse of torment, to seek refuge in Him from torment; or by a verse of glorification, to glorify Him. This is based on the hadith of Hudhayfah, which states that when the Prophet (peace and blessings be upon him) passed by a verse of asking, he would ask, and when he passed by a verse of seeking refuge, he would seek refuge. Some scholars are of the view that this recommendation is specific to supererogatory prayers and not obligatory ones.