Yes, that is strafe jumping.
If you hold down one of the strafe keys, and at the same time move your mouse in the same direction, you will move through the air in that direction.
You should be able to find some "surf" maps to help train your strafe jumping.
Edit:
I forgot that there are also "klimberz" maps to train on. You can search Google for "KZ Maps". Since CS:S uses the same physics engine, you may be able to train your strafe jumping there.
Yukon was intentionally designed to be harder for Engineers:
This abandoned mountaintop coalmine was repurposed by shadowy operatives into a top secret surveillance outpost—one which also, so nobody gets wise, insidiously continues to mine coal. There is also a log hanging in the center of the map—possibly as an example to other logs. Logs that said too much.
Five control points promise a lot of momentum swings in this compact outdoor map, with plenty of tunnels and rocky outcroppings. Plenty of alternate routes ensure that if you can’t get past a well-placed engineer through one tunnel, you might be able to sneak up behind them through another.
CP_Yukon is a community map from the brilliant dual-powered brain trust of Patrick “MangyCarface” Mulholland and Joachim “Acegikmo” Holmér.
-- Classless Update, Day 3
Point 1
Point 1 is extremely poor for defending as Engineer.
If you're building full size sentries, it may be better to build them down in the pit, although that means a Spy can back-cap the point.
Point 2
Point 2 has a few defense spots. One of the best for actually covering the point is at your team's end of the hall when you first come out the door from point 1. You had better have the Wrangler, though, or a sniper at the far end of the can easily take you out.
Another point is past point 2, on the middle route. You can place a sentry on the walkway up. The problem is that, if you place is close enough to the point to be able to see it, it's far enough from the point 3 area for Demomen to be able to take it out.
Point 3
Thanks to point 3 being moved, your best bet is near the point itself, preferably where the fence covers it, so it can't be shot by Snipers (or at least where you can't be shot by Snipers). Your biggest problem here is people sneaking up behind you. You could place it at the very end of the point 3 bridge, facing the point to help counteract that.
Point 4
Building slightly to the enemy's side of point 4 works pretty well, as it covers both entrances to the point 4 area.
Another Alternative
Due to the difficultly in guarding points with a level 3 gun on this map, Mini-sentries work fairly well on it, at least when combined with the Frontier Justice.
Best Answer
It depends.
I have just learned about this line in the December 20th, 2007 patch changelog:
So no, damaging yourself during setup doesn't help your medic charge faster. Additionally, damaging yourself at any one time doesn't help your medic charge faster if he's using the Quickfix.
It seems obvious but worth of noting, however, that this doesn't apply on maps that lack a setup time in the first place. You do want to do "self-damage grinding" on 5CP and CTF maps, and perhaps every other single time you get out of spawn with a medic — if you've seen the pros do it, that's why.
Even in these situations, be aware that not all self-damage methods are equally helpful in making your medic heal faster. You don't have to have a flashing red HP counter to do this; the ubercharge rate reduction kicks in at 142.5% health (except during setup, apparently) and you can be overhealed up to 150%. Here's what it means:
So...
Finally, the buildup rate penalty caused from your patient being healed from more than one source (medic, dispenser,
cart) also applies in warmup, so be careful about that. Move away from that dispenser and overheal somebody who isn't already getting all the love.