If there is water in your oil it will look milky.. since you have Dexcool coolant, it will be milky and orange.

I guess I was in a haze when I originally read your post. If you're not going over 40 but your tach keeps going up then your transmission isn't shifting. like 'erl' mentioned, it could be a fluid issue or simply a vacuum line has come loose.

You could have a corroded battery terminal cable, this is something easy to check. make sure the terminals are clean and tight.

A shift solenoid could have gone out. you'll need a shop to do this work.

I'm guessing you were running around 5-6k RPM the whole way home which could explain why you overheated.

I'd take it to a shop that offers free diagnostics.