I'm sorry, Joel. I jumped to some conclusions because I thought that you were using our PiezoFlush and our cartridges to prepare this 9600 printer. I thought that you flushed the old printer out with PiezoFlush, printed perfect nozzles either before or after you changed the dampers. And then charged it with fresh ink. I looked up your account and I see that you haven't purchased PiezoFlush nor cartridges nor dampers from us. I need a lot more information now in order to advise you.
You wrote that you were able to successfully get the old inks flowing and that you flushed the printer. Then you wrote that you put HDR inks in into the printer without flushing. This is a huge difference and I can't answer the first question about if the new ink clogged with the old ink in the lines without knowing whether you flushed the printer or not - and if you did - what did you use for flush fluid and how did you flush it. And if you did not - how long were the inks sitting in the printer and what brand were they? What did successful mean?
The second question is easier to answer. HDR ink is compatible with the 9600 hardware but not compatible with the 9600 color gamut/space. You would need ICC profiling if color is critical to you.
HDR ink would not congeal if it came into contact with OEM ink, or PiezoFlush, or Piezography ink, or even InkThrift for that matter. It may be another matter if it came into contact with Lyson ink, or Lyson Flush, or a dye sublimation ink, or a solvent ink of some type, and possibly other inks, or flushing fluids, or chemical agents, or if a cartridge was used that was not compatible with one of these fluids or inks. Mixing chemistries is always experimental in nature and possibly with unforeseen consequences.
I need to know a lot more before I can advise whether you have a gelled-up mess on your hands or a machine that is not yet properly prepared for a change in ink.