Never unless it is damaged.
On the V6 it MUST be replaced every 110,000 miles. The 4 cylinder has a chain which requires no. maintenance.
Only when it fails.
Fuel injectors need to be replaced every so often. If the fuel injectors are not working, they may be too old, and need to be replaced or put in properly.
I hate to pop the bubble, but if you have to ask, you should not proceed. The Honda will often smoke out the cam bearings and the head could need replaced. Consult a professional.
the rings are probably bad and need replaced
Freon does not generally need to be replaced. However over time, systems sometimes have a small leak and need to have coolant added. A Freon gauge can confirm if you need to have Freon added.
80,000 miles
The filters are what needs to be replaced most often on the air conditioning units.
Depends on what repair needs to be made. We don't know if you just need to have a fluid line replaced, or if you have to go all out and replace pads, rotors, and calipers.
Depends on what sensor you are talking about. Need more information.
Center bearing should be replaceable after removing driveshaft
This is not a regular scheduled maintenance item. Normally it will last the life of the engine. It is replaced when the engine is overhauled.