heyho
first of all we have a wiki page for most questions

so if you have problems with the interface maybe check there first
http://wiki.amule.org1.)
clients in queue are the guys downloading from ya aswell as the once which have to wait.
so you have 2uploaders, and 1 banned == 3 poeple in queue
also with slot-allocation in preferences you can tweak the amount of poeple you upload to a little.
a client gets banned when he missbehaves, in any way, there is a logic behind it but I wont explain that...
2.)
the priority is the order on "which file to upload first" say you share 5 files, the file with the highes prioriy will get shared the most.
release function is something like "super high" priority, if you set a file release this file will get the most bandwith over all the other.
3.)
well if you have/download copyrighted files thats your problem. IPFilter.dat will not help here. since you never know where the bad guys are
IPFilter.dat is most just to block known IP-ranges from companies which spread corrupt data.
4.)
command line client is --> amulecmd
you can enable it with --enable-amulecmd,
there is also a webserver enable compilation with --enable-amuleweb
for setup read
http://www.amule.org/wiki/index.php/Webserverstefanero