One of the common themes for discussion of Akhenaten is the worship of Aten. I am going to approach this topic as a question and answer style. I think this way it will be a little easier to address all of the aspects of this topic without tangents or confusion.
Who or what is Aten?
Aten is the disk or the visible portion of the sun (Ra/Re/Amun/etc). You could say Aten is the light of the sun which is why Aten is often depicted as rays instead of with the usual Egyptian human or human/animal style. Though there are times in Egyptian history that Aten was shown as a falcon. Aten is the portion of the sun that was believed to bring life, give health and healing. Some Egyptian mythology, prior to Akhenaten, states that life could not go on without the shining part of Ra, which is Aten.
When did Aten worship begin?
Though the worship of Aten is likely from much earlier in Egyptian history one of the first large scale references to Aten is from the 12th dynasty Story of Sinuhe. (Akhenaten was in the 18th dynasty). After the 12th dynasty the worship of Aten increased until during the reign of Amenhotep III, Akhenaten's father, Aten became one of the chief deities.
What is the Silver Aten?
The Silver Aten is another name for the moon used in a few hymns and writings.
Is Atenism monotheism?
The short answer... No. There are several competing ideas about what Atenism is or was in the time of Akhenaten and to the pharaoh himself. One point is that in many of the hymns to Aten other deities such as Ra, Ra-Horakhty, Shu and others are mentioned. Though Amun was shunned other deities are merged with or mentioned with Aten in hymns. This suggests that there were other recognized deities. It is quite common in Egyptian history for various forms of the same deity or merged versions of deities to appear in mythology. One idea is that Aten is no different that this and represents a merger of Ra and/or Horus with Aten. Another view is that Akhenaten practiced monolatry, that is he recognized that there were many gods, did not deny their existence but chose to elevate one above all others. Given that he was the pharaoh and therefore head of the religion as well as the state it seems likely that his personal religious choices could have huge effects on Egyptian religion. There are many other theories about what Atenism really is. In some modern forms it is practiced as a monotheistic religion.
Is there a link between Judaism and Atenism?
It is hard to say whether or whether not Atenism had any influence on Judaism. As there had been several rounds of conquering and trade between Egypt and the Middle East there was likely some exchange of religious ideas. One such idea points to the fact that Aten and God (Judeo-Christian God) are one in the same because of how Akhenaten recorded the deity speaking to him and asking things of the pharaoh such as building a new city. This is likely not the case since this is not the first or last writing of Egyptian gods asking pharaohs to build things. Thutmosis IV, a couple kings before Akhenaten, was asked by the Sphinx to unbury it. Other pharaohs also reference building monuments for similar requests from deities. Some suggest that Moses might have been a priest under the rule of Akhenaten. There isn't much proof for any of this as of now. It is an interesting idea but I would like to see more proof in the form of writings from the time period or just after or some other link beyond speculation before I can say anything on this for certain.
Akhenaten: The Heretic King by Donald Redford
The Amarna Letters from Tyre as a Source for Understanding Atenism and Imperial Administration by Luis Siddall
A Program of Political Theology in Armarna Tomb Art: Imagery as Metaphor by Elizabeth Meyers
UCLA Encyclopedia of Egyptology: Amarna Art by Dimitri Laboury