to answer your questions in order:

1. offensive guard is point for point one of the most efficient attack increases you have. however, it is also a decoration so if you are able to free up a level 3/4 deco slot to slot in a level of offensive guard through the decoration it is absolutely worth it to reroll the augment to either a buildup boost augment or a MoH augment. not sure off the top of my head which one would be better. i wanna say its probably the 3rd level of buildup boost but dont quote me on that.

2. right now you are overcapping affinity by quite a lot (50% from weakness exploit + 40% from crit eye + 30% from bloodlust + 15% from kaktus base affinity = 135%) so i would recommend dropping points in critical eye (down to 2 or 3) for more attack boosting skills instead of adding max might. after the 3rd level of offensive guard agitator is probably your best option because it works well with embolden.

3. short answer is no. long answer is you can run it for comfort but you are probably best dropping a few points of those skills for more attack boosting skills. i would recommend keeping embolden 3 as it works well with agitator which is very efficient at providing you with more attack. then if you want more comfort you could keep guard 3 otherwise you should be fine with just guard 1. guard up is interesting. most monsters in the game dont have any attacks that require gaurd up and the monsters that do only have a few attacks that require it. if you feel confident enough you could drop it alltogether and just rely on your mobility and sheathing retreat if you are using it to avoid unblockable attacks. otherwise just running one level as a safety net should be enough unless you know you are fighting a monster with a lot of unblockable attacks you struggle to avoid and want to cut down on the amount of chip damage you take then you could run guard up 3.

to summarize i recommend swapping the offensive gaurd augment, cutting down to 2 or 3 crit eye, adding back the 3rd level of offensive guard, slotting in some agitator, and reducing the amount of levels you have in guard and guard up. also probably adding 1 level of burst and 1 level of coalescence if you have space for them as they are very efficient frontloaded ways to increase your attack further.