In my view 5...c6 would be ideal against this system, but not if White continues to play in 150 Attack style (i.e. does without a4 and plays Bd3 in response to ...b5)

In answer to your questions:

(1) It may well be that 6...b6 7.e5 is strong.  Since (after 7...Nfd7 8.e6) White is likely to use his h-pawn as a battering ram in any case, he has effectively saved a tempo by not playing h2-h3.  I suppose you could argue that the tempo Black has lost is castling, and that the king is safer on e8 than on g8.  I doubt this, though.  It is not as if it is going to escape to the queenside any time soon! 

(2) It doesn't really make any difference as far as White is concerned: 1.Nf3 d6 2.d4 g6 3.e4 Bg7 4.Nc3 and if 4...c6 or 4...a6, he simply plays 5.a4 when I don't see how Black can do better than 5...Nf6.

To my mind, the fact that White has committed to Nf3 is a good reason to play a Pirc move order rather than a Modern, as it rules ut his two most dangerous options against the Pirc, namely 4.Bg5!? and the Austrian Attack.

(3) You know very well my feelings about the Dutch Defence!

(4) Davies does indeed recommend 1.Nf3 g6 2.e4.  Besides, 1...g6 does not fit in with my repertoire after 2.c4

There are of course various ways to avoid all the nastiness in my initial post - I have already indicated that a favourable transposition to the Czech System is possible at move three, and Black can also play 1.Nf3 d6 2.d4 Nf6 3.Nc3 g6 4.e4 Bg7 5.Be3 a6 6.a4 0-0 7.h3 Nc6!? which does not lead to quite such sharp play.

But the two variations I outlined above have I think  been Black's main responses to this Be3/h3 system so I wanted to highlight potential pitfalls to fellow Pirc players.  The variation has fallen out of favour with White players and has been seen as fairly safe for Black, so it is as well to know if White players are going to be coming at it from a new (and dangerous) angle.

A word of warning to fellow Pirc players out there - Nigel Davies' new repertoire book on the Réti recommends a transposition to a dangerous-looking attacking line against the Pirc when Black plays 1...d6.

1.Nf3 d6 2.d4 Nf6 3.Nc3 g6 (interestingly, Davies gives lines against 3...Nbd7 and 3...Bf5 here, but I can't find anything about 3...c6!? with the idea 4.e4 Bg4 and a Czech System in which White can't play the dangerous 4.f4 line - perhaps this is a way to circumvent the whole issue - although of course it can come up via the 'normal' 1.e4 move order too) 4.e4 Bg7 5.Be3 a6 (as recommended by Pirc Alert and other sources as a good way to meet the 150 Attack, but now ...) 6.a4 0-0 7.h3 and we are into a different system which was really popular back in the late 80s, if memory serves me correctly.

Now Alburt and Chernin give 7...b6 and if 8.Bc4 e6! but Davies does a good job of showing that instead of 8.Bc4, 8.e5 Nfd7 9.e6!? fxe6 10.Bd3! is extremely dangerous for Black.  I haven't analysed this in depth, but I felt compelled to look again at the supposedly quieter waters offered by the standard antidote to this system, namely 7...d5 8.e5 Ne4.

Now Davies gives the sharp 9.Bd3!? Nxc3 10.bxc3 c5 11.h4! when White undoubtedly has a strong attack.
I spent a good chunk of time chewing this over with the help of Fritz 8 and Hiarcs 9 yesterday but without coming to a firm conclusion.

One thing is for sure: 11...Bg4?! is wrong, as after 12.h5! Bxh5? 13.Rxh5 gxh5 14.Bxh7+! Kxh7 15.Ng5+ Kg6 16.g4! White is more or less winning by force.  Davies gives this (citing Dzindzihashvili as his source), and all my defensive tries (including 16...Bxe5, which I think is the best try) met with comprehensive refutations by my silicon chums.

The best I could come up with for Black was 11...Nc6 12.h5 c4 13.Be2 f6 14.hxg6 hxg6 15.Nh4 fxe5! (15...g5 16.Ng6 Rf7 18.Bxc4! dxc4 19.Qh5 is incredibly dangerous and well worth spending some time analysing as there are some very pretty variations, but definitely to be avoided by Black, as a lot of those pretty lines end up with him being mated in mid-board!) 16.Nxg6 Rf7 when Black's king is obviously a source of some concern, but he does have some counterplay in the centre.

One important point is that after an eventual ...exd4, cxd4 White can try to get a rook lift in via Ra1-a3, with potentially devastating effect.  In some lines, Fritz doesn't like this at first as it usually means that d4 falls, but once the rook gets over to g3, Black falls apart.

It may be that Black's central play is sufficient, but it is certainly a line to be aware of - and more than a little bit wary, too, in my view.

Any thoughts?