Hobbs is not the same as tacho. Tacho is proportional to engine RPM, whilst Hobbs is linear with time, depending upon how it's turned on and off, which will vary between aircraft.
It is normal on CofA aeroplanes to log take-off to landing for both airframe and engine. Most permit light aircraft do the same.
Microlights, radically, log start to stop for the engine, and brakes-off to brakes-on for the airframe. In theory anyhow, in practice I think that most log brakes-off to brakes-on for both.
For pilot logbooks, brakes-off to brakes-on is ALWAYS correct for civilian pilots (the UK military use take-off to landing - I have no idea about other countries militaries).
Whether you log as a pilot to the nearest minute, five minutes, or decimal time, is entirely a personal choice. In my experience five minutes is most common, followed by decimal time, followed by nearest minute.
Hobbs or Tacho time are not correct for a pilot logbook.
Tacho is often favoured for rental rates, as it's not subject to interpretation, and if you treat the engine gently, the aeroplane is cheaper to rent - which tends to encourage people looking after the aeroplane.
G