Double-Round Day

PLAYING routinely without considering the specifics of a position is a recipe for disaster.
Fortunately for me, my opponent this morning in what is a double-round day in the Mariánské Lázně Seniors focussed too much on avoiding defeat instead of realising he was much better.
Spanton (1943) - Ian Aird (1830)
Queen's Gambit Declined, Exchange Variation
1.c4 e6 2.Nc3 d5 3.d4 Nf6 4.cxd5 exd5 5.Bg5 c6 6.e3 Be7 7.Bd3 Nbd7 8.Qc2 h6

What should White do with his dark-square bishop?

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9.Bf4?!
This is a popular move that has been the choice of some strong players including Nimzowitsch, Fine and Ponomariov, so it is probably presumptuous of me to call the move dubious, but the more popular 9.Bh4 definitely seems better.
9...Nf8?
Slow.
I intended meeting the stronger 9...Nh5 with 10.Nxd5?? Only after moving did I see that my idea of replying to 10...cxd5 with 11.Bc7 fails to 11...Bb4+.
10.Nf3 Bd6 11.Bxd6 Qxd6 12.0-0 N8d7 13.Rab1 a5 14.a3 0-0

How should White proceed?

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15.b4?!
The position may look ripe for a routine Minority Attack, but my main analysis engines Stockfish10 and Komodo9 prefer 15.Rfe1 or 15.Rbc1, and it soon becomes clear why.
15...axb4 16.axb4 b5
Stockfish10 still prefers White although Komodo9 reckons the weakness at b4 more-or-less gives Black equality. Either way, my pawn-thrust at move 15 looks to have been premature.
17.e4?
Fighting for the initiative at all costs, but the main effect of the text is to create a second weakness, at d4.
17...dxe4 18.Bxe4
Or 18.Nxe4 Nxe4 19.Bxe4, when Black's backward c pawn seems to offset White's two isolated pawns.
18...Nxe4 19.Qxe4?
Again mistakenly thinking I was getting an initiative. 19.Nxe4 looks equal, one possible outcome being 19...Qd5 20.Nc3 Qd6 21.Ne4 etc.
19...Nf6 20.Qe5 Rd8 21.Rfd1?
Black is better anyway, but the text invites a strong pin.
21...Be6
As I saw almost immediately after playing my last move, Black is virtually winning with 21...Bg4.
22.h3 Ra3 ½-½
Even stronger, according to the engines, is 22...Nd5. Luckily for me, IA played the text and offered a draw. White is very much on the back foot, so I was obliged to accept.