Presumably te1/7 is connected to xe-0/1/0.If you have a standalone switch then the VME is the out of band management interface. Do you have anything connected to this port as you have not mentioned it?
If you have two switches connected by a single link and therefore no loop, there is no requirement for spanningtree to pass traffic between them.
The console port uses RS232 and not Ethernet and IP. To log in through a management port, you would need to know the IP address and use SSH or Telnet.
I don't know Cisco that well but they have out of band management ports so I would assume the concept is the same. The management port is for traffic that accesses the device's control plane so is used for traffic to and from the router only and does not allow traffic to traverse the device through that port. If you are trying to ping across the link either to or from the VME interface it will fail as this would be considered transit traffic. You are correct that the use of the management port may require a separate out of band network and this is often the case with service provider networks. On enterprise networks it is quite common not to use this port and instead use an in band interface such as a VLAN L3 interface. You configure this as an IRB interface and associate it to the VLAN. Please see below.
set interfaces irb unit 30 family inet address 192.168.10.5/24
set routing-options static route 0.0.0.0/0 next-hop 192.168.10.1
set vlans v-30 vlan-id 30
set vlans v-30 l3-interface irb.30
set interfaces ge-0/0/4 unit 0 family ethernet-switching vlan members v-30
The Me0 and VME interface on a standalone switch are essentially the same thing. When you stack switches in a virtual chassis, you use the VME and this IP can be accessed through any one of the physical management ports.
I am not sure what you mean by L2 routing.