/pdcc on|off (for several versions now, you only use on or off, putting any value after pdcc does nothing)
If turned on, tries to speed up dcc sends by sending packets ahead of acks.
/fsend is fast send, turning it on should help speed up dcc sessions
The mIRC fileserver allows other users to access files on your hard disk, the commands you showed are only for fserv. A fileserver is initiated by using the /fserve command which initiates a DCC Chat to the specified user. You must specify a homedirectory. The user will be limited to accessing only files and directories within this homedirectory.
In mIRC, type /help dcc server protocol and notice the difference between fserv and send protocols.