It depends on the company. At many companies any number of shares entitles you to attend, though many companies set a minimum number of shares in their bylaws (I think public companies can only limit this to a maximum of 1000 shares, and IIRC nearly all publicly-traded companies set a limit to avoid single-share troublemakers).

Speaking also depends on how the bylaws say the agenda is constructed, but I've never seen any where a share would entitle someone to a spot on the agenda. There are sometimes spaces for comment, and I think the rules for how those are selected/filtered are set in the bylaws.