I think you mean 8. Qe4+, winning the black knight and putting a nasty pin on the rook on a8 after 8...Be7 9. Qxd5 Nc6 10. Ne5

9...Bxf8 then 10. Kxf8 d6 is better than just 9...d6 but white still has an advantage

id=sf115 - you might want to emend that to 9...Bxf1 10.Kxf1 d6. Although Black would have exchanged a fairly active piece for an idle one, the disruption to White would have been worth it.

the knight is not really "side-lined" as it has little options to develop another way. c6 is not available and d7 is ineffective as b6, c5 and f6 are blocked and e5 is attacked by the white knight and a passed pawn on d5 doesn't look good for black

the knight belongs on d7 where it controls the e5 square and so preventing the e4-e5 pawn break. On a6 it does nothing and it does even less on c7!

maybe castling strait away could be better as later the possibility of ...Qd7-b5 could be awkward

Nb5, taking advantage of the fact that it cannot be threatened with a6, to go on with Bf4 (I prefer to do that after h6, in order to place the bishop on h2 if threatened by Nh5), is not a winning attack, but at least takes advantage of the weakness of d6.

white has a nice position now with a space advantage and control of the centre.

Possibly Black ought to start looking to his own assets: in particular the Q-side pawn majority. The game is very double-edged at the moment (tho' I'd probably prefer the White position here).

If black accomplishes b5 / c4 advance, he can give a good square for the a6 knight (c5). He can support it with his rooks... white has to act quickly to get concrete shape to his advantage. And white cannot move his king pawns to attack. Another plan for black can be Ng4, to prevent e5. And, if h3, Ne5. After the knight exchange, the d pawn is free, but I think that is not a great advantage, since it cannot be supported by other white pawns and the inactive e7 bishop can go to d6 and easily block it, where white's Nf5 is easily rejected by g6.