Explanation:
The observation from the gold foil experiment by Rutherford was that, while most of the alpha particles went through the foil almost unaffected, a small fraction of the particles were deflected in directions with large angles away from the original path (including bouncing straight back). This was unexpected and led to a complete revision of the model (as relates to your part 1).
The nuclear model proposes a spacially small but massively charged nucleus. Due to its small size, most alpha particles will pass through the atoms of the gold foil unaffected (they "miss" the small nucleus). But some of them will come very close to the nucleus and those will be deflected strongly by its charge. This is one of the main arguments explaining the observation and speaking for the validity of the nuclear model.
