Third, no, pissing Kreia off won't lock dialogue away for you, provided you really piss her off. The Exile has some selective amnesia at parts (forced by the writers) so the player can be introduced to people and concepts they would otherwise know, but aside from that the Exile has no amnesia.
Second, there is no lost memory thing, and I'm not really sure where you've gotten that implication from. Without the restorations and the bugfixes it provides, TSL is going to be a shadow of an experience for you. First, are you using TSLRCM? Provided you're playing on PC and you're not, it is quite literally worth it for you to restart your game just to play with it.
