Alternate Character Creation Question(s)

Is it at all feasible to start an alt character without playing them (paying the additional PC each event), thus earning build?
If so, do I assume correctly that the alt PC, upon entering an event, could spend those amassed build points and thus start at a higher level?

Determine Your Starting Build
Determine how many points of Build your character will start off with. As a starting character you are given 50 Build. If you purchased additional Build, you may use it at creation. All build that you have earned, from these sources or other sources (such as retired PCs or NPCing), you may immediately spend on skills before starting the game. A character may start only using rules and skills that are published in the Knight Realms core rulebook.
Regardless of how much build the character starts with, all normal limits (such as pre-requisites) apply at character creation.
Once the PC is in the game, you can spend any remaining build as quickly as prerequisites allow.

From the rulebook

Can an Alt character buy back a past event? If so, would that include any bought build for that past event?

Yes and Yes.