How do I set up a section of text on my home page to rotate through, rather than stay static?
This should be relatively simple to implement, although depending on how the page was designed may require reworking some of the existing page layout and css.

As far as craft is concerned the data could be stored in a few different ways; perhaps in a separate channel, table, or matrix field. Setting this up on the craft-side is trivial, and would not require any special plugins.

On the front-end content could all be loaded when the template is initially rendered (by simply adding a few lines of code to the template), or loaded as needed using javascript and ajax (by creating a separate template used to render just the text segments as requested). Although if it's truly only text, I would opt for loading it all at once on initial page load. Transitions would normally be done using some fairly simple javascript and/or css transitions.

There shouldn't be any technical limit on the number of items you could display; but there probably are some practical limits where it would start to get clumsy for one reason or another.

If you need more specific code examples, please leave a comment, and I can add more detail.