See the Developer's Zone (www.ni.com/zone) for specifics on USB (search for "USB").
"1.Is it doable?"
- In short "no".
- USB is similar to FireWire (IEEE 1394), and no framegrabber is required. We offer an IEEE 1394 IMAQ driver to interface FireWire cameras with LabVIEW & CVI.
"2.How to connect USB-type interface with IMAQ PCI-1424 board."
- You will need a USB driver for the camera. The 1424 is not required.