Are the weapon effect bonuses a flat number bonus or %-based? Also how effective are these? Should I pump rares/SRs into one that's maxed to get the weapon level skill capped or just level other weapons (if applicable) to get more overall stats? What about rare weapon bonus vs SR vs SSR? Is rank 10 R weapon better than SR weapon of different element?

For Eidolons, I know only the effect is taken into account for main eidolon and friend's, but do the stats of all eidolons equipped go into your character stat boost? I would assume yes but wanted to verify - in other words should you slot all reserve eidolons with good effects/highest stats and not care about the elements?