Of course you can. Many novels throughout history have quoted from the Iliad to great effect. It can help you establish themes, create a sense of grandeur, or even provide a contrast to modern ideas in your novel. For instance, if your novel is about war and heroism, a quote from the Iliad about Achilles' heroics can be a great way to introduce or emphasize those concepts. Just make sure that the quotes are relevant to your story and not just randomly inserted. Also, proper citation is essential not only from a legal perspective (since it's in the public domain, the citation is more about academic and literary integrity) but also to help readers who may be interested in exploring the original source further.
Sure. Quoting from the Iliad can add depth and historical context to your novel. Just be aware that you should quote accurately. For example, if you are writing a historical fiction novel set in the same era as the Iliad, quoting it can make your story seem more authentic. But also, depending on the length of the quote, you might need to consider how it fits into the overall flow of your novel. And, as mentioned before, always credit Homer (the traditional author of the Iliad).