I see some things on my engine and trans that I don't recognize. Can someone tell me what they are and what they are used for? The pictures came out very big, scroll through the pictures to see my questions. Thanks in advance.
First picture - left side of trans - two sensors
Second picture - right side of trans - one sensor
Third picture - water pump housing - one sensor
Fourth picture - left side of engine at spark plugs - is this a sensor or something else? What is it and what is it for?

Trans left side - what are these?

Trans right side - what is this?

Water pump housing - a coolant level switch?

Engine left side between spark plugs - what is this and what is it for?