Can i guard break or jump attack while holding a shield with 2 hands?

No unupgraded shield should have 100% phisical defense.

While it is true that the buckler and target shield have the longest Parry frames (making parryin easier), they also have some of the longest wind up and recovery frames from the parry, the buckler will probably not allow you to execute the stronger guard break Riposte while the enemy is standing before they fall down, and parrying too early will leave you more vunerable than a faster shield. (example being, the enemy has just ran out of stamina but you expect another attack and parry the air, the faster shield will leave stood there like an idiot for less time than the buckler will, probably not enough time for them to attack you, or move behind you)
its all down to personal preference, there's a very interesting page on parry frame data i encourage you to look at.
there is No good answer as to the "best" parry shield, with enough practice, all shields and weapons will perform well. just. don't try parrying with the Zweihander to start with.

The rose shield is this game's grasscrest shield

Just use the twin dragon shield. You're welcome.

Which of these shields do you think most resembles the Bonewheel Shield, I'm trying to create Jimmy Darksoul, the ds2 version of John Darksoul

most of these shields are very fashion souls unfriendly : /

is it just me or there are a lot less 100% phisical shields in DS2?

At least we have some shields with almost 100% thanks to defence scaling and a decent number of shields that can reach a 100% in other stats