ADB,
There is no overdrive indicator in these new Volvos. The arrow, so long as it is not blinking, indicates you are not in D or drive. Or, the winter button is pushed. The solid yellow arrow also means you will not be in 4th gear. When it comes on again, verify that the W button is not engaged and that you have it in drive. If you are going down the road and there is no one behind you, try shifting to "N" and seeing if the arrow goes out. Then just pull back one notch to drive, no need to stop when doing this.
As for engine heat, check your temp gauge on the dash. It should be pointing to 3 o'clock. And, yes, the engines are normally hot. The center vent on your dash has a separate control to allow outside air to enter the cabin. This vent draws air from the area just in front of the windshield and can be initially hot if the car has just been restarted or sitting in the sun. Not to worry, it will/should draw in ambient temp air within seconds.
You need to have someone test the voltage in the lighter socket. It should be at 12V. If it is much higher, like 14-17V, then your voltage regulator will be at fault. It is a bummer to lift up your center console to replace that one lightbulb, but it is still easy to do. http://www.volvospeed.com/Repair/SV70console.php

A noisy steering wheel is usually attributed to a bushing at the base of the steering column. It needs to be cleaned and regreased. Easy DIY. see:
http://www.volvospeed.com/Repair/70steering.php

Klaus

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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)