Off the top of my head I don't see how these issues are related.

1) A high idle as you describe is often associated with a failing block temp sensor. The idle may or may not be too high to start with a cold engine and continue to rise as the engine warms. I've seen idle speeds listed here going as high as 1800 rpm as the engine warms, with closer to 1300 being more common when the problem begins. Inspect the wiring under the intake manifold (the rearmost sensor). The resistance can be checked against specs. If you dig around there are graphs you can use, just make sure they're for the correct temp sensor. From the 700/900 Pocket Data Booklet, for the common Bosch sensor p/n 0280130-032 used in the LH injections systems, as a quick check you want to see
8.26-10.56K Ohms at a sub-freezing -10 degC (14 degF)
2.28-2.72K Ohms at room temperature 20 degC (68 degf), and
290-364 Ohms with a well warmed engine at 80 degC (176 degF)

But first, make sure the ECU knows it's supposed to be idling when the throttle is released. Check the TPS for the click (and if needed using the OBD diagnostic socket test). Insert a fold of 20 bond paper at the throttle stop screw and it should still click on opening the throttle otherwise it's set too close on the hairy edge. Also make sure the IAC valve isn't sticky and that it can be controlled by the ECU. Tap solidly on the IAC with the end of a wood stick while the engine is idling high to make sure it doesn't change -the idle will change and become closer to normal if the IAC is sticking/dirty/worn. If the IAC has failed there's also an OBD diagnostic test you can use to verify operation of the IAC (the tic-toc test). See the OBD section of the FAQ here.

2) For the speedometer, the common issues with 940 speedometers are exactly as Art says. A quick inspection under the rear will tell you if the speed sensor wiring on the diff is damaged or broken. If not then it's likely the speedometer itself. As he noted, it's in the FAQ. That would also explain while the odometer is still working, albeit it reading incorrectly. Hopefully the shop will be able to put it right for not too much money.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now