1) When you focus you pick the discipline. And no, you don't need to know a connected power.It's getting serious... I might actually get to play an Esper soon.
When creating the character I found a few things not 100% obvious:
1. Psionic Focus: Do you have to chose which discipline you are focusing when you are taking the feature or when gaining the Focus? Follow up: Do you have to know a power of the specific discipline? (Someone might just want to have the specific benefit without actually having the discipline)
2. Since the "Mind Strike" seems to be something like the Cantrip for the Esper... can an Esper use a Mind Strike if he gets an Attack by a Marshal's Commanding Presence (or similar effect)?
3. If you Ready a manifestation, I assume that (like spells) you already manifest the effect and then keep it "ready", requiring concentration. Since that would "destroy" a Psychic Focus, could the readied effect (maybe only if it is of the discipline of your focus) be "parked" in the focus, only overwriting the benefit of the focus until the readied effect is released?
4. Follow up to Ready: I'm guessing you roll any augmentation dice the moment you get the effect ready and not when you actually release it?
Pretty sure more may follow
2) I would say yes. It is, essentially, a cantrip.
3) Yes. Concentrating to ready an action is it's own thing that totally makes sense for Psionic Powers.
4) Sadly, yes. I always thought it was silly that wizards waste their spell slot if they don't -use- the spell they readied, but RAW that's what happens. So Psi Dice would also be rolled up-front to maintain parity...
Unless you're at my table, in which case spells and powers that are readied require concentration but don't expend the slot, or roll psi dice, until they're actually -used-.