How does using F1-F4 on allies work? Is there something similar for use on enemies?

Question

In the tips and tricks for Shen there is an example that you can use your ult by pressing F1-F4(or is it to F5?).

How do you know who on your team is which F? Does this also work for for using shield, heals etc.?

I know you can use your spell by clicking on the icon of your ally(sometimes useful in TF's, by getting dragons/barons because you can't target them easily).

Is there also something similar to the F1-F4 system to use on enemies (by pressing tab or something?)

This could be useful to use your stun on them, and be sure it would hit them.

Answer 1

Ok, to help assist you I will use Shen as a primary example, since he is my main tank and I feel most comfortably using him. So his ultimate is called Stand United, this allows him to teleport to an ally and add a shield to them to help prevent them from being killed. So on the left hand side of the screen you have images of your teammates champs. You can click F2/F3/F4/F5 to select the team mates on the left in the order that is listed on the left side of the screen image or you can click on the image and it casts your spell on that champ. If an ally champ is in the cast range for a shield you can click on them and it will cast or f2-5 depending on your option. The F keys only relate to your team mates. As for enemy hotkeys to date there are no hotkeys.

Answer 2

You can left-click an enemy and their icon will appear in the top right and you can click on that to use abilities and such, but short of that, no.

As for telling which team member is which key, they're arranged in the top right of your screen as well, top being lower and lower being higher.