Is it worth upgrading Guild Bonuses for events?

Robenator

So I've just leveled my general guild level to 10 which unlocks some neat stuff every level so you can personally make yourself more powerful, I've also leveled my Guild War and Protect Seireitei up to lvl 8, but I don't know if they are worth it, Attack for Guild War seems worth it I guess, but 0.2% max hp per level for Protect Seireitei? Is this % of HP added to your characters in the event or to the gates you must protect?

I'm not sure if it's worth it, but I'll probably level it anyways, since the smallest amount of difference that can make us win is still worth it I guess.

streetking

it only worth to lvlup 2 in both guildwar(GW) n protect seireitei(PS) with give 1% attck for GW 1%hp n 1%PS... just focus on lvlup ur guild 1st unless u know there no player left to join ur guild then u can continue upgrade ur GW n PS hall...

MisterMusashi

Well I know it works in conjunction with the 20 or 30% (I forget) bonus for defending, but I don't know whether it stacks multiplicatively or additively.
Also I'm still not sure how the damage for Fireball is determined and calculated so I don't know how effective the bit of extra health is in that regard.

And streetking, leveling up the guild still gives 0.5% bonus to silver/experience from Stages as well as allows for upgrading stat boosts in the guild camp which gets a huge boost every... 6 levels? I think it was 6. Or was it at 11?