I would probably drop your Focus mapped key and use the options in your Character Set to do it automatically. If you did that because it didnt work with the Character Set options, it's probably going to work now that the addon is enabled

If you're using the auto-generation, the Hot Character will always Focus on himself. That means your macros that are split into 2 actions can be 1 action to All, instead of using a different one for the current Character, because [target=focustarget] will have no effect when you ARE the focus target.

You seem to be on the right track, though.

p.s. Manually doing this:
Code:
/castsequence [target=focustarget] reset=15/combat Frostbolt, Fireball, Fire Blast
Is the same as just putting
Code:
/castsequence reset=15/combat Frostbolt, Fireball, Fire Blast
And checking "But First", "Assist Hot Character", and "Restore target afterward". If you use the targeting options provided, you can seamlessly switch to and from FTL at a later time if you so desire. Simply enabling FTL would automatically fill in the FTL conditionals for you, as opposed to using target=focustarget.