Cayin i5 digital audio player questions


I am finally taking the plunge into high resolution audio and am really looking forward to recieving this new player i bought online today.

As a total newbie (only discovered IEMs are headphones today), I am hoping for some solid advice from anyone who's already got one or similar.

My questions are....
1). Any recommendations for over ear headphones circa £100 budget?  I cannot afford to buy Mezzo 99 Classics or DL1770s.
2). Any recommendations on in-ear headphones for same budget (~£100)?
3). Where to buy / download / trade hi- res tracks?
4). Should I also be investing in a headphone amp for (1) and (2) above and, if yes, any recommendations again.
5). Any recommendations for speakers for circa £100...i have read that bluetooth is a lttle flakes yet ie. Might be best to get wired speakers until f/ware resolves Cayin i5 Bluetooth issues.
6). Can my existing large CD collection be upgraded to hi-res FLAC format? 

I listen to almost all kinds of music excluding country, jazz and classical.
Hope you can help,