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Hi, allow me to try and clear up some of this confusion.

The winged-bull and winged-lion colossi have several names in Akkadian, including: aladlammû, lamassu, and šēdu, as well as apsasû when identifying female variants of the beast. However, these terms are not all solely used to describe the winged-bull (or lion) colossi.

The term lamassu actually derives from the Sumerian word làma, a bipedal apotropaic spirit: the "patron goddess" of an individual. Làma are feminine in nature, their masculine variants are called alad in Sumerian, and šēdu in Akkadian.

Here is a làma or lamassu according to its original definition.

Now, for the second question.

This is the god Aššūr according to the Assyrian people themselves. He is a late-era deity, who absorbed the traits of the earlier Sumerian gods Enlil (King of the Gods), Ninurta (champion of the Gods and wielder of the bow), and Utu (the Sun, and origin of the sun-disc in Mesopotamia), among others.

Here is another representation of Aššūr, and here he is blessing an Assyrian king. Aššūr is on the left, the goddess Ištar (Sumerian Inanna) is on the right, the king is in the middle. Finally, Here we have Aššūr leading a divine procession. He is the frontmost left-facing deity, standing atop the Mušḫuššu-dragon and the lion, his sacred totems.

Concerning the griffin-demon, I'll quote directly from Gods, Demons, and Symbols of Ancient Mesopotamia, a foundational work on Mesopotamian culture, art, religion, and symbolism by Jeremy Black and Anthony Green:

With possible antecedents in the Old Babylonian Period, and with close analogues in Mitannian art, the griffin-demon first appears in his familiar form—a human-bodied figure with bird's head and wings—on Middle Assyrian seals, and became a very popular figure in Neo-Assyrian art, especially in the ninth century BC. After the seventh century BC the figure is rare, but occurs on Seleucid Period seals. The private quarters of the palace of Assurnasirpal II (reigned 883-859 BC) were dominated by reliefs depicting this creature

In the Neo-Assyrian Period figures of this type were explained as representations of the Babylonian Seven Sages, and groups of seven figurines of them were used as foundation deposits to protect houses and palaces (see: building rites and deposits)—alongside very different anthropomorphic figures and figurines of the fish-garbed figure (also supposed to represent the Seven Sages).

ETA: In order to fully approach each aspect of the original questions, I decided I'd also quote the entry on Nisroch from Black and Green's work. It can be found below:

The Assyrian king Sennacherib was murdered in 681 BC, apparently by Arad-Mullissu and another of his sons (they had been passed over for succession in favor of Esarhaddon). According to the Biblical account (2 Kings: 19; also 2 Chronicles: 32, Isaih: 37, and Tobit: 1), Sennacherib was killed while worshiping in the temple of his god, 'Nisroch'. It is not clear to which Assyrian god this refers: it has been suggested that this is a corruption of Ninurta, but this is unsubstantiated.

When in the nineteenth century AD Sir Austen Henry Layard excavated the palace of the Assyrian king Assurnasirpal II (reigned 883-859 BC) at the city of Kalhu (modern Nimrud), he discovered large numbers of bas-reliefs which depicted images of a winged eagle-headed figure. Referring these to the Biblical story, Layard labeled the figures 'Nisroch' (in view of Ninurta's supposed character as a bird-god). As a monumental figure-type in the palaces the eagle-headed man is now known not to be present as late as the reign of Sennacherib, the term 'Nisroch' is still occasionally found in modern art historical literature for this figure, otherwise known as the griffin-demon.