Nor I, this is not extraordinary and the Portugese have been shaping up for a confrontation with the EU central powers ever since their last internal elections at the tail end of last year. All of the PIGS are anti-austerity to different degrees whereas the central powers are as we know them all too well.

I wouldn't describe it as "blackmail" (but I can also understand why a Spanish newspaper would use that terminology about the Portuguese, or the Catalonians for that matter).
It is a normal part of political (in this case) chicanery prior to the next big round of agreements/summit.
All of us do the same thing when "buying off the wife in order to take the next riding trip over the horizon".

The Portugese may have more success with their budgetting than the Greeks managed last Summer because the circumstances have changed with the Brexit question.

The Mandate:-
Fiscal policy sure. Although the EC is supposed to be the executive body responsible for implementing the policies of all 28 nations, all 5 presidents can be seen to be totally engrossed in the preservation of the Eurozone.
Hence the interests of all of the EU nations receive scant attention at present.

Monetary, no - as you say, that lies with the 19 alone (I think that is the number who are members of the eurozone).

But, yes, these points do go to the heart of what our PM has been negotiating with the other nations, the EU bureaucrats, the EC bureaucrats and who ever else might get to sit up to the table. e.g. Will the £ support the Euro?
(there was a moderately interesting wee snippet a few days ago, when the peanut farmer, ex-President, was wheeled in for an interview on some new item - he fluffed his lines and, fairly quickly for an old man, corrected himself. To wit, "Britain staying in the EU is good for America" which is probably true from their viewpoint).

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Dave