Magic
Magic isn't quite dead yet. Indeed, given the correct circustances, and the correct preperations, a pratictioner of the arts could move a mountain. However such circumstances are likely to be hard to come by. In general the approach one might take to magic is to prepare potions and spell components in advance, such that they can be used at a moment's notice - or to aquire the debt of some supernatural entity who will repay it by aiding you in your aims.
Magic in Society
Magic was once considered an ideal profession for a gentleman of means. With the magical decline, things have changed. Certainly there remain members of society who study the arts - the majority are more concerned with theory, but a frew practical magicians remain, oftne in secret, preserving their art for future generations.
Amongst the less civilised classes, practical magic is more prevalent. Few have the knowledge to back their works up, or make new discoveries but many exploit the knowledge of their forefathers for personal gain. One or two still are able to stand out as remarkable, compared to the creme of the educated crop - but they are few and far between.
Creatures
Mythical beasts are mostly memories. Essentially anything intelligent that isn't human, angel or demon is considered to be a faerie. Although some people might make exceptions for giants and dragons. Faeries havn't been seen in England for a long time (perhaps they were just myths) - it is rumoured that some still exist in Scotland and Ireland, and adventureres who travel overseas bring back stories of strange creatures and strange magics (but they are probably exaggerations)