As to angels, for one thing, they aren't what people think they are.
They're not embodied (except in those few instances recorded in the
Torah); nor are they the winged, fairy-like things soaring about in the
air shooting arrows at young couples or hurling down lightning-bolts that
many think they are. And what has come to be known as "guiding angels" are
never cited in our holy books.
Instead, angels are incorporeal, absolutely invisible agents of G-d's will
who carry out all His wishes and could be said to be stealth and subtle
catalysts for change. Each one is charged with dominion over a particular
and distinct province of its own; and they differ from each other both by
kind and function.
In fact, as Ramchal puts it, "everything that comes about in the world --
both good and bad -- takes place with the input of angels". So there are
both" good" and "bad" angels; or better yet, angels that focus upon
beneficial outcomes and others that concentrate on harmful ones (known
as "angels of destruction"). Thus, angels are the most common albeit
invisible and unobtrusive Divinely-commissioned, fully-engaged and active
participants in everything that happens in the universe.
Now, while Ramchal doesn't touch upon this here, it's important to know
other things about them. The most exalted of them are termed "Archangels"
and are known as Michael, Raphael, Gabriel, and Uriel. Angels have often
appeared prophetically to certain rare individuals to announce portentous
events, either good or bad. They told Abraham about the forthcoming birth
of Isaac and informed Manoah and his wife of the birth of Samson, for
example. G-d has sent them to protect us, as happened after the Exodus
from Egypt when one was sent to lead us to the Land of Israel and to
destroy the antagonistic peoples in our way, to mention only one instance
among many others.
And finally, it's important to know that angels existed before the
Creation of the universe, they sit as judges in G-d's court, they
accompany Him when He appears to man, and they often "walk to and fro
through the earth" to report back to G-d about mankind's actions.
Rabbi Yaakov Feldman has translated and commented upon "The Gates of Repentance", "The Path of the Just", and "The Duties of the Heart" (Jason
Aronson Publishers). His works are available in bookstores and in various
locations on the Web.