Mate your a commercial pilot now, any flying that "you" pay for is tax deductible. The confusion is that it's not GST exempt (unless you do it prior to CPL test).
Not true.
Any training you undertake must be for progression in the existing company. You can't do a MECIR and claim it as a tax deduction to gain employment at another company if your company does not require it.
Same goes for ATPL subjects, or anything else.