i've never tried Mycelium so i can't say anything about it. check out its dedicated board and ask your questions there: https://bitcointalk.org/index.php?board=231.0

as for holding, it is a speculation question. it is hard to answer. in short term BCC price will surely drop hard. and depending on "how hard" it may or may not be able to recover. we still don't know how much money they are willing to throw at it. the miners dedicating hashrate will surely lose a lot of money for a considerable amount of time. and a lot of other things to consider before saying anything about its future.
one thing is for sure, nobody is happy about it and it has so little support. and i will personally hold less than 5% of my reward because i have some plans for it (for testing some stuff)