Was hoping to clarify an accounting concept:

A company owns both preferred and common shares. A potential investor has an opportunity to purchase all the common shares of this company. At this company, there are 500 preferred shares with a cost and redemption value of $10 and $12 per share, respectively, and a 6% mandatory, cumulative dividend yield. These shares will be retained by the current owners of the company. Furthermore, capital stock on the financial statements are recorded as $55,000

I am a little confused about this. Does " These shares will be retained by the current owners of the company" regarding preferred shares mean that the potential investor wont be purchasing these shares? When the investor purchases the common shares, how will capital stock be effected? Do dividends on preferred shares still need to be paid after the investor buys all the common shares?