They usually just recruit generally, and put people into whichever team there are vacacies in. Since there are more teams that deal with Corp/M&A, there's a larger possibility of getting placed there. But there's always a chance of other teams too, like IP, if they have vacancies.

Not usually, but some do provide a preference practice area, however, the common ones are disputes and corporate. Whether the preference is actually considered is totally subjective to the entire recruitment process, whether they are expanding teams and the candidate pool. In my experience, only Trilegal and CAM were the ones to offer IP and Competition law as practice area preferences. Most of these firms rely on PPOs and internship-based recruitment as the teams are comparatively not as big as the Gen Corp or disputes team, and even with high attrition, the demand isn't enough to make that additional effort of recruitment.