Before I buy , i want to make sure: will a 430exII fire by "seeing" the light burst from other flash sources? and if not, what canon speedlite can do this?
No, the 430EX II does not trigger by generic photo slave.
However, it can be remotely triggered using a compatible Canon system flash trigger. Those include the ST-E2, or a 580EX/EXII, 600EX flash units.
In addition, some of the newer Canon cameras, supporting what Canon calls the "Integrated Speedlite Transmitter feature" (popup flash) can also trigger this flash, Those include the 60D, 70D, 7D, and the T3i(600D). There may be some even newer bodies that support this as well but not older bodies like 40D, XTi/XSi.