Totsu:
For this current fight with the Ronin what happens if I decide to parry on my secondary action phase? What do I roll against and what is my target number?
All secondary bcs are 50% and all bcs are always rounded down. So your chance to parry you roll a 5 bcs. Note the rules though, since even failure can increase your ac.
Totsu:
If I parry I can still attack on my next bap, correct?
Yes. But note the parry is only good until your next ap, not a full turn.
Totsu:
If I attack for a second time what will be my chance to hit? Is it 11/2=5.5 rounded to 6 then +1 for my level then -3 for opponent modifiers = 4?
I already mentioned your bcs for secondary phases. When you say ‘a second time’ I assume you’re talking about atemi-Waza second strike. The rules for that are slightly different.
If second striking on your BAP, both attacks get a -1, and the second is at 50%. So your first attack is bcs 10, and your second is bcs 4. ALSO, attacks against you are at +1 and you lose your defense UNTIL YOUR NEXT BAP. Defense, btw, is your level if your using a budget that is a bonus skill. So, at first level using atemi-Waza, your ac goes down one AND people are at +1 to hit you until your next BAP.
If second striking in an Sap, same rules apply but you’re already at 50%. So first attack is 11/2=5-1=4 for sap, and 5/2=2-1=1for the second bcs.
And please note that while the +1 to hit you is cumulative if you second strike on both BAP and sap, you can only lose defense once.
Totsu:
Does my opponent get any bonuses to hit me if I attack on sap?
No. Not unless you second strike him on your sap. See above.