HI, in answer to your second question: the Dark Ages refer to the period after the collapse of the Mycenaean civilisation when there was a rapid decentralisation of states into smaller settlements and a near total loss of culture, such as writing and art. However, that said, there was never a total lack of art in this period, and that is where the Geometric Period classifications come, they refer to the art style of this period, starting with Proto-Geometric. A good example of this art style would be the Dipylon Vase from Athens.

A good starting point for me would be The Greek World edited by Anton Powell. It's a book that covers Greece from the Mycenaean Age down to the Hellenistic period. It is a book divided into numerous of essays by several historians, so you can be sure you will get some good stuff. Just to confuse you, there is another book titled The Greek World by Simon Hornblower that covers the Classical Period and is typically recommended reading for undergraduates.

Irad Malkin is an excellent source of information on Greek colonisation. He discusses it in numerous of his books and articles, and he also goes into how ethnicity and religion played a part, rather than simply the natural and political causes. Here's a post about Greek colonisation where I include a very short bibliography.

There is no shortage of material on ancient Greek warfare, it may be one of the most published about topics in the field. That being said, there are two books I'd recommend you begin with because they provide a good overview of the debates. Men of Bronze edited by Donald Kagan and Gregory F. Viggiano typically subscribed to the traditional school of thought regarding the Hoplite revolution. Hans van Wees' Greek Warfare: Myths and Realities is an excellent book that covers warfare throughout all of ancient Greece (Hans van Wees is also an amazing historian of Archaic Greece, so anything by him is a decent read). I'd also recommend just searching Hoplite warfare on JSTOR, you'll find bucket loads of articles discussing Hoplite battle, although sadly not a lot is dedicated to the light troops comparatively.

Alternatives to Athens edited by Roger Brock and Stephen Hodkinson is a good source of articles discussing alternative political systems, rather focusing on Athens, as was very common in Classical scholarship. Furthermore, Stephen Hodkinson is one of the leading voices in Spartan studies, although his work can be a little dry, but it is very informative.

A good new voice in scholarship regarding slavery is David Lewis (he was my dissertation supervisor so I'm a wee bit biased). He has a lot of articles regarding slavery all across the Greek world, from the supply of slaves to manumission, from Phrygia to Crete. Here's his book Greek Slave Systems in their Eastern Mediterranean Context, c. 800-146 BC.

And one last one which doesn't really have anything to do with your question, but because I love them. Nino Luraghi's The Messenians is a great read about a central, but often overlooked people of Ancient Greece who took part in nearly all of the great conflicts of the Greek world. A true underdog story if there ever was one.

One tip I recommend is searching for Classics or Ancient History degrees online, a lot of universities will have a recommended reading list for prospective students.

​

I hope this helps!