Re: Hardest instruments to play
I think tabla scare a lot more people than they should. They are just as hard to master as anything else... Well maybe harder to "master", but under the right circumstances and guidance, you should be able to play the basic bols and accompinaments and some variations in an acceptable manner in a relatively short amount of time.
Advanced concepts of matras, tal, and variations on bols would confuse the heck out of anyone without a teacher. You need a teacher, and to some degree you need to understand the Hindi notation (I've been told) to truly understand the subtleties between notes that otherwise look identical when written in English. But for all intents and purposes, I think you can get away with the basics and sound halfway decent after a few months, to a year or so of practice.
It is a difficult and very precise type of percussion instrument. I'm on board with anyone else who thinks any instrument would be difficult to "master" (and I still detest that word as it relates to musicianship).