USB 2.0 DisplayLink via a USB 3.0 bus?

[Maryland, USA]

To add USB 3.0 to my W500, I've ordered this 4-port USB 3.0 Expresscard. Currently I run two L220X 22-inch monitors (1920x1200 each); I plan to run four. My third and fourth monitors will be driven by DisplayLink adapters (USB to DVI). Now that I've discovered how useful it is to mount one monitor above another, I may even get a fifth and sixth. I know that USB 3.0, as implemented in the W500's Expresscard, provides 2.5gbps--five times the bandwidth of a USB 2.0 bus. But this leaves me with several questions:

1. How many different USB 2.0 buses are available on a docked W500? Just one, with all eight ports (3 on the W500, 5 on the dock) sharing 480 Mbps? Two, with a bandwidth totaling 960 Mbps?
2. If I connect one DisplayLink adapter to a native USB 2.0 port and the other to the Expresscard, will the latter be a bit faster, since ithave its own lane and won't need to share a bus with other USB devices, like my USB speakers?
3. Let's say I connect four USB 2.0 DisplayLink adapters to the USB 3.0 Expresscard. Since the Expresscard has five times the bandwidth of USB 2.0, wioll EACH Displaylink enjoy a full 480 Mbps of bandwidth?
4. I already use one Displaylink adapter, the Lenovo, which is based on the DL-195 chip. Would I be advised to stick with Lenovo for all subsequent DisplayLink monitors?