"If strong ideas and actions offend you, read no more" helps the reader understand that a young woman in the historical context of the story, was not permitted to think or act in ways that could be considered "strong".
Certainly the other statements could lend you some ideas about the time period, for example the year, sailing on a ship as a means of travel, or being called a lady, but the idea that a young woman could not do the kinds of things that other people could do, tells that this will be a story that is different for girls. Charlotte's adventures on the ship were things that, normally in 1832, a girl would never have had a part in.
