How to get a HTML element from a string with jQuery

Just wrap the html text in the $ function. Like

$("<div>I want this element</div>")

Yes, you can turn the string into elements, and select elements from it. Example:

var elements = $(theHtmlString);
var found = $('.FindMe', elements);

Just use $.filter

var html = "<div><span class='im-here'></span></div>"
var found = $(html).filter(".im-here")

If you are loading a page dynamically from a server then you can target just one element from the loaded page using the following form with .load()

$(selectorWhereToShowNewData).load('pagePath selectorForElementFromNewData');

For example:

$('#result').load('ajax/test.html #container');

Where:
#result is where the loaded page part will be displayed on the current page
ajax/test.html is the URL to which the server request is sent
#container is the element on the response page you want to display. Only that will be loaded into the element #result. The rest of the response page will not be displayed.