Nitpicking, but I couldn't help but notice some of your stuff is out of date. Like this rifleman example. You can't take 3 shots at the very least because if he hits you once with a charged shot he can two-shot you. Also, sorry I botched up the quotes in this and will have to resort to using actual quotes.
"For example, a rifleman shot deals 60 damage. Theoretically, it should down the medic in 2 shots, since his HP is 120. However, after the rifleman takes his shot, your health will regenerate. You can take 3 shots at the very least. The autoregen also makes the medic perfect at harassing. He can run in, deal damage guerrilla style, and retreat to safety. While he hides, his HP will regenerate, and he may attack again.
Keep in mind, your speed is 1.09, and the Firebug's is 1.09"
Also, correct me if I'm wrong, but isn't the medic slightly faster than the firebug?
- Fighting the Constructor:
Treat him like a gimped runner. He's slower, deals much less damage, and doesn't have a double jump. His redeeming feature is the autogun, which many say is overpowered. Medics are very good at taking out poorly placed autoguns. This is because of the arc in his needles. You can arc over crates, arc up a staircase, arc up a wall; the possibilities are nearly limitless. Almost any autogun can be taken out by a medic without any loss of health. Sometimes it's better to rush the autogun, if you're pressed for time, or being pursued. Go over the autogun and keep jumping straight up and down. If the constructor is near his autogun, see if you can arc your needles into him, it usually causes him to pursue you. Take him out before the autogun. He is very similar to the runner, and his weapon shows it. He is extremely fragile because of this.
You didn't really mention the constructor's ammo in this. You don't have to, but I'm saying it would probably be easier if newcomers reading this guide knew that he had around 8 or so shots of ammo.
- Fighting the Quote/Curly:
Use the usual backpeddle while shooting technique until they pull up a bubble shield. Keep firing, but now jump towards it. That's right towards it. Jump over the Q/C and keep your cursor on it. Backpeddle away. Repeat as necessary. This class is built on rushing in and pinning you against a wall. Don't let that happen. Also, if you are being chased, it's blades will push you away, helping you escape.His blades decrease in power the longer he fires them, take advantage of this, but also take note that a bubble shield will stop you in your tracks.
It would be helpful if you mentioned that, unlike other classes, quote/curly technically has infinite ammo.
And you might have mentioned this, (you probably don't have to add this, but still) it would be nice if you had a section about the medic radar, which shows the directions of injured teamates when they shout

and also automatically sends out a signal when they are on fire.