After the fall into sin, in Genesis chapter 4, we read of Abel keeping flocks and bringing the best of the firstborn from the flock as a thankoffering to God. Can we deduce from that statement that now humans started to eat meat? Or did Abel keep flocks just for the wool and the milk and the hides? Scripture is silent, so a careful Bible reader cannot be definitive.

Some commentators have indeed speculated that mankind might have started to eat meat after the fall into sin. Perhaps the descendants of Cain, who quickly displayed a godless character in many other ways (violence and polygamy as evidenced in Gen. 4:23-24), also displayed a disdain for the original command from the garden and began eating meat. Perhaps believers joined in. But it remains a "perhaps." All such speculation is simply that--speculation.

However, later the Bible clearly states in Genesis 9 that God allowed an expansion of the menu. (verses 3-4 of chapter 9) God specifically allows meat. Regarding your second question. The "fear and dread of you" falling upon the animals is really a wonderful display of God's gracious protection for humans.

After the flood, there are only eight humans alive. Contrary to the creation, when Adam and Eve lived in perfect harmony with each other and with the animals, Noah and his family leave the ark and live in a sin-infected world, sin evidenced even in the natural kingdom (see Romans 8:20-22). How quickly humans could have been overtaken and overrun by the rapid population growth of the animal kingdom! God insures the safety of Noah and his family. Even though outnumbered, and really rather defenseless, God protects the small enclave of human survivors. God places "the fear and dread" of humans upon animals as an act of love and safe-keeping.