I do not understand combat.

You calculate your totals and then you roll the dice.

Where are combat options?
Well you can try to disarm, grabble, what ever but what about Aggressive attack, defensive attack, feint?

Is it a house rule to add +1 to defence score and reduce 1 from attack score??!

What about fatique, the way I read it, you only lose fatique levels when boosting your attack or defense score.

4th edition used to demand roll every round if I remember correctly.

The older editions' options of All-Out Attack or Defense are covered by the Fifth Edition option of Exertion. You spend a Fatigue Level to get a bonus equal to your combat ability to either attack or defense for one round.

I would not recommend a house rule letting you borrow points from Defense to put on Attack or vice versa. It tends to make whoever gets the first attack just maim the enemy with one blow, and end the fight on the first roll. Especially when combined with the exertion option, it's too overwhelming.

As to Fatigue, there is no round-by-round Fatigue roll. Combatants willingly spend their Fatigue Levels through Exertion. As with any strenuous activity, the storyguide can call for fatigue rolls after the fight.

That fatique system sounds a lot better, I hate rolling fatique all the time.

Perhaps that fatiquing defense is enough...