First off, while there are plenty of practice exams, no VEC (the organizations that operate the Volunteer Examiner system for amateur radio) will provide you with the actual exams. Be mindful that there is a finite question pool for each exam element and practice and official exams are both drawn from the same pools. However, given the size of the pools relative to the number of actual exam questions, it's unlikely that you would encounter the exact same exam with the exact same questions and in the exact same order at a session even if you had the official exam generation software.
Better than simply cramming the exam questions is to study the subject areas they cover. One place to start are the ARRL study guides as well other publications such as the ARRL Handbook, Operating Manual, Antenna Book, and so forth (the Basic Radio series may be an even better starting point).
Also, be aware that
W5YI-VEC is the other nationwide exam coordinator. Check their site for exam locations. ARRL and W5YI are the two most popular VECs.
As for the antenna polarity difference between 10 meter amateur and CB operations. On 10m amateurs are generally oriented toward DX via ionospheric propagation while on CB operations are limited by rule to less than 150 miles. As CB operations are limited to communications to the horizon and slightly beyond by direct skywave, vertical polarization became preferred due to the vertical whip being favored on mobiles (the same convention is used on Part 90 mobile services as well as amateur FM operations). On direct skywave propagation, cross polarization costs up to about 30 dB of signal loss.
As amateur 10m operations are mostly oriented toward beyond the horizon skywave via ionospheric skip, either vertical or horizontal antennas are employed with horizontal preferred on towers and masts so the elements are perpendicular to the mast to minimize couple and pattern distortion. Once a wave passes through the ionosphere its polarization is unpredictable so it can arrive at the other station at horizontal, vertical, or any degree in between which is responsible, in part, for signal fading. So choosing one or the other is mostly operator preference. In some areas, amateurs engage in direct skywave for local communications as in CB and vertical antennas are preferred for the same reason as in CB or amateur FM operations.
Good luck!
