In that case you will use the "tagged" keyword for each VLAN you send to the WINGS including the Student and Voice VLAN.
It will be something more like this:
vlan 7 name DATA-WINGS by port
tagged ethe 1/1/20 to 1/1/48
router-interface ve 7
vlan 123 name VoIP-WINGS by port
tagged ethe 1/1/20 to 1/1/48
router-interface ve 123
vlan 100 name WAN by port
untagged ethe 1/2/1
router-interface ve 100
No only the ve interface is treated like a virtual router port. Specifically, this port will show up as a directly-connected route for whatever subnet you assign to it (based on its IP and Mask). This serves as the gateway for ALL devices within this VLAN to get off their respective subnet when they send packets to a destination IP in a different subnet via this IP as a default gateway.. This setup with an entire VLAN of ports mapping to a virtual routing interface (VRI) is in-fact an extremely common configuration for this or any vendor's multi-layer switch with the only difference being the terminology and configuration methodology. This setup is like having a router and a switch inside the same chassis.
The overhead is of no concern whatsoever for the switching; the ICX 7750 is a workhorse with a line-speed ASIC to do the switching up to the full-speed of its switching capacity, which is a minimum of 1.92 Tbps depending upon which model. That works out to where this device can run 40 Gbps per interface on all 48 interfaces at the same time.
You are probably running 1Gbps or 10Gbps connections via media types 1000BaseSX or LX or 10GBaseSR or LR to the wings. Depending upon if you have multimode or singlemode fiber.
Regardless, when you can look at the routing table if you do a "show ip route." It isn't going to list it for each physical port but rater it is going to list it by its VE... something like this given the last post I made. You may have some Rip routes"R"; since, you mentioned you use RIP. It is also fairly common to have a default route 0.0.0.0/0 listed with its next-hop IP shown int the gateway column instead of "DIRECT." Based on my last post, It will be something like:
SSH@YOURICX7750#sh ip route
Total number of IP routes: 4
Type Codes - B:BGP D:Connected O:OSPF R:RIP S:Static; Cost - Dist/Metric
BGP Codes - i:iBGP e:eBGP
OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2
Destination Gateway Port Cost Type Uptime
1 10.1.0.0/16 DIRECT ve 7 0/0 D 12d13h
2 10.250.120.44/30 DIRECT ve 100 0/0 D 12d13h
You really have to worry about the dual-mode or access-ports "untagged" only on the edge switches out in the wings.
Basically, in the above example, you would bring both VLANs 7 and 123 into the edge switches as TAGGED; since, they would have an 802.1q tag present on each frame crossing that link. Then they would go to the end computers untagged to transmit that same layer-2 frame on the LAN segment without an 802.1q tag, so it is understood by the end computers or printers (for example).
Usually phones are Tagged, so you can share the same physical ports. Dual-mode was your native-vlan. Now you just use untagged and tagged in 08.0.80 and later build families. Th configuration is simply more streamlined.
If you have multiple pairs of fiber to the wings, I would highly suggest the switches in the wings be stacked, and that you have a stack of ICX-7750's. You would then be able to make a Link Aggregation (LAG) to each wing using LACP. Essentially, you would double the bandwidth and reliability in that you would be able to loose either ICX-7750 and still have half the LAG's virtual interface up and operational.
In the closets with the edge switches, I would terminate half the LAG on the active and the other half on the standby units in the stack. This way you could loose any one switch in the stack and still have at least half the LAG operational maintaining connectivity. With hitless-failover, you can even replace a broken switch in a stack without restarting the entire stack!