With the information below, can I upgrade straight to ASA 8.2(5) and ASDM 7.1(4) or do I need to do an incremental upgrade for both software and asdm images?
Should be no problem with the ASA software since you are essentially only upgrading to latest maintanance realease of the same Major and Minor software level.
I dont think you really need to worry about the ASDM at all. Seems to me that the latest ASDM software is compatible with ASA software all the way from 8.0