The shield has been on for a couple turns but I doubt that would count as a prep. I'd probably have to say she focused on the shield or something to add to it but it's her spirit doing the work and would always be able to focus on the shield so it would always stay at base power unless effected by outside sources. 

By her dodging it, that would be up to the timing of his swing and how perfect that could be rather than her able to dodge. I'll buy that he'd anticipate her to tun straight at him to take advantage of tht moment, so her speed of arrival would be the main variable.