"4. fpc 0 ports can not be converted to virtual chassis on ex 4200."
This is incorrect. Ports 0-23 can be configured as 1Gb copper vc ports.
test@test> show virtual-chassis vc-port local Interface Type Trunk Status Speed Neighbor or ID (mbps) ID Interface PIC / Port vcp-0 Dedicated 1 Up 32000 3 vcp-0 vcp-1 Dedicated 2 Up 32000 0 vcp-1 0/23 Configured -1 Down 1000 test@test> show chassis hardware Hardware inventory: Item Version Part number Serial number Description FPC 1 REV 19 750-021255 xxxxxxxxxxxx EX4200-48P, 48 POE CPU BUILTIN BUILTIN FPC CPU PIC 0 BUILTIN BUILTIN 48x 10/100/1000 Base-T PIC 1 REV 04 711-026017 xxxxxxxxxxxxx 2x 10GE SFP+