I had these questions as well, and didn't get a lot of response.
But this is what I did,
The supplier that provided me my hotend gave me a bit of "Muffler Putty" with my hotend, which is great as a glue for high temperatures, but I wasn't sure how well it conducted heat.
So I used a tiny bit of Artic Silver Thermal Paste for both the heater and thermsistor, just to help conduct heat on the inside.
NOTE: These heatsink pastes are usually only rated up to 200deg C, but they just 'dry out', but should still help conduct heat.
On the ends/outside I used "Muffler Putty" provided to firmly glue the heater and sensor in place.
I think wrapped them both firmly in place using Kapton Tape, because I noticed that after a while, the muffler putty dries out, and may allow sensors/heat to pop out.
SO
1) Heatsink Thermal Paste to conduct heat on the side/end of the sensor
2) Muffler Putty which can be found at any hardware store to 'glue' the heater/sensor in place
3) Fully wrap it in Kapton Tape to make sure it stay's put.