ill try and touch both. for the record, im muslim and although my perspective is not limited to that which many find "popularly" islamic, im aware that i may tend to lean that way, but idigress.
sentient is to be self-aware if you and i are accurate in the meaning. as ive read in the quran and have sensed to be implied in the "judeo/christian" scripture, all things in the universe follow the will of the lord in their own way. to use the human parrallel as we have no other real reference (as youve implied by the subject of this post) self-awareness begins with consciousness, consciousness as far as we've reasonable assertained is a product of the "caused" electro-chemical processes in and of our nervous system thus creating various electromagnetic fields, for lack of a better term. this idea is supported by the notion that changes in the overall electrical activity coincide with changes in overall consciousness. also note that all "things" in the universe are basically EMF's so all things could possibly have a consciousness, albeit with different tendencies for affection, whereas a stone's EMF would be much more stable(affected by fewer things) than a parameceum's than a fly's than a dog's than a human's. this is where i believe the idea of free will comes from.
im a firm believer in the concept of destiny as evolved by the will of "the lord" or more commonly known as the law of the universe. i cannot realistically imagine an instance that is not somehow the product of causation as bound by the laws of only that which is possible in our universe. therefore, even though im not aware of all the micronic details of the causation, from observing the worldaround me, i can only come to the conclusion that all is the product of what caused it to be. this is the only constant and foundation represented in all scientific and analytical research.
i dont believe that "free will" is one's ability to "make" any decision. on the contrary i believe that "your decisions" are those decisions in the universe that make/affect your consciousness rather than the decisions your consciousness makes itself (though please not that present state of mind is always a factor in future state of mind). to tie this idea of "free will" to self-awareness, i believe that the "free" in free will refers to the fact that the human version of awareness is not limited to any preset of parameters. for instance your dog is affected by hunger and habit and taste etc. as its prerequisite to eating, whereas people can be affected as well by nutrional values, cultural preferences, etc... there is no limit to what is able to enter our human realm of awareness (as is eloquently represented by this website).
free will refers to what ideas we possibly have access to/that will affect our consciousness. has anyone here imagined any limits to what can be imagined? i hope not. this is our special relationship with "the lord" as no one can deny the justice of causation as one of the "lord's ways"
at least, thats what i think