Maybe, but the weakness on c3 is not exploitable for the moment. Meanwhile, the pawn there stops Black's knight coming in at d4 with a view to forcing White to double pawns on the f-file (for what that is worth to Black, or to White...).

True, and that block is partly what the c3 move was all about (it also hinted towards a center-board takeover with d4 as well), but the vulnerable pawn is something I only pointed out as a possible target for a developing plan. I did feel like I was giving too much of black's perspective in this annotation, and not enough of white's. So it is a good thing you bring it up.

Precedents?

Thanks. I corrected it. I need to be more conscious about the spell checker.

15.Qa4 seems to be the more active choice. White's position looks fine, here, but the difficulty is to come up with a plan for improving it. It seems to me that maybe it is a little bit easier at this point for Black to arrive at a realizable plan...

I think that's a good way to put it, actually. The position is certainly equal still, but black's options are less ambiguous.

The knight's retreat to d8 did give White the opportunity for the central break that ought to have been considered at least. The line 16.d4 exd4 17.exd4 "justifies" White's previous Q move, as the e-pawn retains its protection after 17...Bxf3 18.Nxf3, and White has into the bargain nasty looking threats along the white diagonals leading to Black's king.

But maybe White could have made better use of her time, here. The bishop is not threatened - not yet, at any rate. It is wise to assess the consequences of waiting until a threat develops (since it often transpires that the threat can not be answered!) but it is equally important to find out whether need to respond at once to a threat that hasn't yet materialised. White could have considered 17.d4 here with a very reasonable game in prospect.

Agreed. In fact, white's bishop would not be under a direct attack for a while, given that the only semi-reasonable attack would involve black's push to d5 (hanging the e-pawn). I do believe that b3 is a better spot for the bishop, though. It gives the bishop more squares to cover while allowing the c-pawn some movement, should the need ever arrive.

Probably the Q recapture at e6 is correct, but I would have found ...fxe6 very tempting...

I hadn't considered it, but it does look like it would be just as good. I do like that it gives the rook a half-open file.

White had to try d3-d4, either now, or, if it required preparation, very shortly. Black has created for himself fine attacking chances against White's king. White has to counter in the centre, in principle as the most effective response to a flank action, but I don't think White has any option here. Black's attack is a little way off just now, but White hasn't much time to waste.

Not a bad try!