With regards to the second part of your question related to the configuration of virtual chassis over long distances the setup you are looking for is referred to as "Extended Virtual Chassis Configuration" . You'll find more details on it here in this virtual chassis best practices guide :
http://forums.juniper.net/jnet/attachments/jnet/switch/9816/1/VC-Bestpractice-guide.pdf
If you are configuring it on an EX 8200 Series switch ( with external route engines ), you'll need this :