How to treat and...

The general approach you should always follow on diagrammable "Must Be True" questions is, "What's the easiest way I can diagram this to help me see how to connect these statements?" The first claim says, basically, "If we do not redistribute wealth, we can't alleviate economic injustice and we'll get intolerable economic inequities." The next claim leads off with "If the inequalities become intolerable ..." That's a sign that the question wants you to connect the first sufficient condition ("Unless our nation redistributes wealth"/"If we do not redistribute wealth") to this next claim. Sure, we could write make an intermediate conditional statement that says "If we keep our current system, we will get intolerable economic inequities." But doing that will only make it harder and more time-consuming to connect the first sufficient condition ("Unless our nation redistributes wealth"/"If we do not redistribute wealth") to the "If the inequities become intolerable" claim. Other times, diagramming a conditional statement that follows an "and" will make it easier to see the connections the question wants you to draw. Take this example: "If we diagram carefully, then we'll see connections, and seeing connections will lead to better LSAT scores. And of course, if we get a better LSAT score, we'll have a stronger application." In that case, I'd argue that diagramming "seeing connections will lead to better LSAT scores" as a new conditional statement would make it easier to see the connection for many test takers. As with anything on the LSAT, you'll get a better sense of what to diagram, and how to diagram it, with lots and lots of practice. So keep working at it!