This is the french exchange variation, and as far as I see it, the game is still in its opening phase. And we know what that means: development, development, development! Neither player has finished deploying their pieces to their most effective squares, and they should focus on doing this to begin with.
Therefore I think that your suggested 10...Bf5 is a perfectly reasonable move, since it places black's LSB on a very active diagonal, and even manages to restrict white's movements somewhat. Then black should aim to improve the b8-knight by putting it on, say, f6, and connect the rooks. Fighting for the control over the e-file is a very common theme in the French advance, so doubling the rooks over there is a reasonable course of action.
Now, what will white play in the meantime? Just like black, white should focus on developing his pieces. At the moment, the c1-bishop is blocked by the d2-knight, which is totally unacceptable, so white must at some point reposition the d2-knight. White's idea with Qb3 may seem appealing, but since it really doesn't threaten anything particularly dangerous (as you demonstrated) it's more a question whether white really wants the queen there to begin with.
Regardless, the d2-knight has to go somewhere, and most likely it will go to g3 via f1, or to b3. Then white will clear the first rank to double the rooks on the e-file (in this context Qb3 has a point, since it helps white clear the first rank with tempo).
Worth mentioning, due to the placement of the e2-rook, is that after 10...Bf5 whenever white moves the d2-knight, black will be able to play Be4, threatening to take on f3 and damaging white's pawn structure. This could potentially gain a tempo for black in some lines.
In general, after both players have finished developing, I think that black should be at least slightly favoured due to the bishop pair and white's somewhat clumsy development.
One final note: under no circumstances will Kh1 be a good move for white in the next few moves. It simply wastes a tempo when white is already struggling to develop the remaining pieces. Even after 10...Bf5 11.Qb3 b6, white does not go for the simple threat of taking on d5 with Kh1?!, since black still has to develop the knight on b8. Black would love to play Nd7 to develop the piece, but that is not possible to do immediately, since then white really can take on d5. Thus, if black prepares Nd7 by playing c6 anyway, the tempo wasted on playing Kh1 could be more effectively used for other things.