Glojo,
To help out here - the IPP is about what the acronym means - an Integrated Power Pack. It's a fairly substantial rotating shaft machine located aft in the fuselage. It's designed to combine the functions carried out on previous aircraft by a number of items of machinery, such as power generation, starting, cooling and hydraulic power. It can run on aircraft fuel, in a turbine mode, but usually runs on bleed air from the engine. It's no more a second engine that a gas turbine starter unit is.
The heat issue from the exhaust is something I was closely involved with while on the project. The exhaust from the IPP is actually less hot and fast than that from the current APU on the F-18, and the assessment at the time was that while it posed a potential issue, it was manageable, using the same sort of techniques the USN and USMC had done for some time. If that's changed since I was on the team, I'm not aware of it.
Best Regards as ever,
Engines.