Islamic philosophy is a development in philosophy that is characterised by coming from an Islamic tradition. Two terms traditionally used in the Islamic world are sometimes translated as philosophy—falsafa (literally: "philosophy"), which refers to philosophy as well as logic, mathematics, and physics; and Kalam (literally "speech"), which refers to a rationalist form of Islamic theology.
Peter Adamson, Philosophy in the Islamic World: A History of Philosophy Without Any Gaps (he also has a podcast)
Ayatollah Murtada Mutahhari, Understanding Islamic Sciences (ICAS Press, London)
Allamah Tabataba'i, The Elements of Islamic Metaphysics (ICAS Press, London)
I am sure other people will also have suggestions!
Do you mean his own works, or other people's commentary on his works? His books on Islamic Philosophy are available in pdf. En Islam Iranien is only partially translated into English. There are various websites that list his publications.
Yes, every thing in this life is relative and Allah The Glorious is the Only Absolute Fact.
Every thing created in this universe is possible in its existence ممكن الوجود , but only Allah , The Creator is Must in His Existence واجب الوجود.
Thank you for your question. There are two types of realities you are asking about in your question; those related to matter and those that are not.
As for those relating to matter, matter is not everlasting. It is constantly in a state of change as that is one of the characteristics of what makes something material. Therefore, anything related to matter cannot be absolute as it is linked to something finite. So movement for example is linked to an object, an object is limited by time and space and therefore movement cannot be absolute. The same is the case for direction as any direction is in opposition to another direction and so cannot be absolute.
As for those things which do not always have to relate to matter such as love or truth, if they are related to the Absolute, they can be absolute and objective, but when they relate to a person or a thing they will be limited by the limitation of their locus. So a human cannot absolutely love another human as that is a limitation of human beings, however God can absolutely love. Humans cannot understand the absolute truth, but God is the Truth. Humans can come closer to the absolute reality and be a manifestation of the absolute reality and indeed it is reported from the Prophet (saw) that Ali (as) is with the truth and the truth is with Ali (as).
This is generally in line with what the scriptural sources say and you can look into it further by studying reports in books such as the Tawhid of Shaykh Suduq or in Nahj al-Balagha.
May you always be successful.