Does Swift Strike get enhanced in Dragonblade

The thing is, even though Swift Strike is relatively quick, Symmetra's sentries will not lock on until Genji has exited Swift Strike, and is still in range of your sentries.

So to answer your question, if the Genji swift strikes past your sentries, and ends in a spot that is out of range, the sentries will not stop it.

Situation 1: McCree's lock-on delay for each player is increased proportional to the amount of effective health gained through Lucio's ult. Given that McCree is allowed to use his ult unhindered, you are correct in your assumption that Lucio's ult would do very little.

That said, the delay caused by Sound Barrier is likely to afford your team the time to either prevent him from going through with it or at least to find suitable cover.

Situation 2: It is exactly as you have said. In my experience, and as indicated by a player's account of his experience in this reddit post, increasing a player's effective health removes McCree's lock on effect; however, I am not sure if this resets the delay entirely or if it just increases the delay proportional to the health gained. Either way, it's worth investigation.

In short, Lucio's ult is very effective at countering Deadeye.