Machine consciousness is relatively immature as a modern scientific and engineering interdisciplinary paradigm [1]. Nevertheless, we could try to answer the former questions with a good degree of confidence. 

 

In contrast to weak AI, strong AI claims that an appropriately programmed computer is a mind. Generally speaking, strong AI supposes that it is possible to build machines that can truly reason and feel. In this context, machine consciousness would refer to the feeling part of the hypothesized strong AI machine. From my point of view, most of the forms of reasoning are possible without any consciousness or feeling capability. Such a being would be a so-called (philosophical) zombie [2]. Therefore, we could argue that machine consciousness is key to “conscious” strong AI, but could be neglected in a relaxed form of “zombie” strong AI. This could be true if reason and consciousness are really independent, but what if reasoning and consciousness are intimately linked? Does more reasoning power involve more awareness? In my humble opinion, this question cannot be answered unless the real nature of consciousness is understood. Such an account should include the phenomenal aspects of consciousness (see definition of Qualia) [3].

Even though machine consciousness can be easily identified as a science fiction paradigm, I think it can have a key role in the realm of weak AI. Applying human consciousness models to machines and their programming is a form of bio-inspiration. We can study the human cognitive processes related to consciousness (like attention or propioception), and use the same principles in artificial machines. A much harder subject is the phenomenal dimension of consciousness, whose comprehensive underlying biological foundations are not known. This is one of the gaps to fill in the field of strong AI.

[1] http://www.conscious-robots.com/en/conscious-machines/the-field-of-machine-consciousness/what-is-machine-conscious.html

[2] http://consc.net/zombies.html

[3] http://plato.stanford.edu/entries/qualia/