1) Can I use Pure Defense while I'm preparing Yuuse Batojustu?

2) Can I use Second Weapon: Dfensive Style with a shield?

1) I would say yes, because while both restrict the actions you can take, neither of them are in and of themselves actions.

2) Yes again, but remember that you need to spend DP to use the shield as usual.

Thanks, even if I have renounced to Yuuse Batojustu in favor to Grafull Parry.