When taking a drop do you have to actually measure using a club …In the case of an unplayable lie a drop of a few inches from where the ball is may be all that a player requires…If the drop is obviously within 2 club lengths without measuring is that legal?....we seldom measure 2 club lenths behind the tee markers…it’s assumed to be within 2 club lengths when teeing up

Welcome to the forum Miles, I personally don’t measure short drops but if I got a rule nazi then I suppose I could be questioned, the important thing as far as I am concerned is marking the position and then if it rolls away then it might have to be measured. Remember also that you can measure with any club so that would give me 92 inches or 7 foot 8 inches to play so short drops should be pretty safe.

A few inches drop with unplayable ??

I wouldnt advise that ….if the ball rolls back between the roots of that tree , or into those rocks , or back into that bush ….there is NO free redrop ….you must take another penalty if you want to drop again

Not obligatory, but wise to measure.
For some guidance see the second para to the answer in Decision 24-2b/2.

(I’ve never seen anyone name a thread after themselves – very innovative;))

There is no requirement in the rules to use a club in determining a drop position. Nor is is there any requirement to follow the procedure in identifying the nearest point of relief.
However if there is any doubt about the accuracy of the resulting drop it is strongly recommended that the process is followed exactly. O/w is could cost penalties if challenged after the stroke.