Logging Instrument time : 

• If you're an instructor while instructing : you can only log instrument time when in actual  IMC 61.51(2)

• Otherwise you can log instrument time only when operating the aircraft solely by reference to instruments under actual or simulated instrument flight conditions.

Currency : 

Condition 1 :You're current if within 6 months you did : Six instrument approaches. Holding procedures and tasks. Intercepting and tracking courses through the use of navigational electronic systems. 

Condition 2: If you LOST currency for more than 6 month (6 months after condition 1 has not been met) then you need an IPC : Instrument Proficiency Check

Minimum Altitude for IFR flight : 

2000 feet over mountains (above the highest obstacle within 4nm of that obstacle)

1000 feet everywhere else (above the highest obstacle within 4nm of that obstacle)

if ATC clears you for a CRUISE ALTITUDE XXXX you're free to fly from the minimum IFR altitude up to the Cruise altitude, and you don't have to ask for a clearance to fly an approach

IFR Fuel requirement: 

Enough fuel to fly to the destination airport, then fly to the alternate airport, then add 45minutes on top of that

VOR Checks 

VOT : Max error is 4 degree 

LOG : Date, please, bearing error, signature 

1 dot of deflection = 2NM off course 60NM from the station, decreasing proportionally as you get closer. 

if you have 2 dots of deflection 30NM from the station you're 2nm away from course

if you have 3 dots of deflection 30NM away from the station you're 3NM away from course

if you have 4 dots of deflection 120NM away from the station you're 16NM away from course

Standard rate turn 3degree per second / 360 degree each 2 minutes 

DME Usability range : gotta be 1+mile away from the DME for each 1000ft above the facility. eg: if you're 2500ft above the DME, you gotta be at least 2.5miles away for the reading to be accurate