All references to left and right are taken from the driver's point of view siting in the driver's seat looking forwrd be it a LHD or RHD.
So right engine bank is the intake side where the throttle body etc is located.
I recently fitted 2 new O2 sensors and used cheapo ebay universal replacements which involves a little wiring ( joints included) to the original loom and plug.
You need to get as much height as possible to get to the sensors but no special tools are required.
The connector plug is a little awkward to release but once this is done I used a 22mm ring spanner (push the plug through it 1st) to release the sensor then unscrew by hand.
The new sensors are coated with anti seize compound but you need to align the threads very carefully when refitting i.e. make sure the sensor is square to the hole and only finger tighten until established.
As I mentioned I used universal sensors so you will need to cut off the original plug and fit this to the replacement, ferrules and heat shrink sleeving is supplied ( you will need a crimping tool), The instructions also provide the wire colours from OEM to the replacement.
It took me about an hour to do both on mine.