First answer: whatever sounds best
Second answer: start with your "main" or most important tone item... In your case probably the Euphoria, then add pedals one at a time until you are happy with the results.
Third answer: If it were me, I'd do #2, and probably end up with a chain that looks like:
(Filters)
Xotic Wah
Q-Tron
EQD The Depths
(Dynamics)
Xotic Compressor
(Fuzz)
Velvet Fuzz
(Drive)
Euphoria
(Delay)
Tape Echo
(Reverb)
Headroom
(Tremolo)
Supertrem
(Sample and hold)
Freeze
(Looper)
Ditto
(Accompaniment)
Trio
That's because I like Vibe before Fuzz and OD, Delay->Reverb->Tremolo and want all the Freeze, Ditto and Trio at the end. I also usually like the comp always on if I'm not using Fuzz. Since those are all True Bypass, I might also go Wah, Depths, Fuzz, buffer/always on pedal. Also, Q-Tron, Trem, Wah, Compressor and Freeze are completely up to you and your style.
Fourth Answer: See answers 1 and 2.