I would really suggest taking a course, as @zephyr826 has pointed out above—a good teacher will really help with the interpretation (always key in history), and, though it won’t sound like much fun, any writing assignments (should you, as an auditing student, choose to write them) will help you think about the material and get it ingrained.
On to your specific topics—just finished my Crusades seminar at school this past spring. Not actually my favorite topic, but I can give you a bit of help there. Christopher Tyreman is one of the main-stream-ish authors on the Crusades right now; he’s done a variety of books which I have encountered in several classes. On the most basic level, he’s done an overview of the Crusades in the ‘Very Short Introduction’ series, which you can get for under three dollars (last time I checked). He’s also done several other books; I am desperately trying to recall which one we used in basic Medieval History, which did a good job (so far as I recall) of discussing the modern-day implications of the Crusades, as well as some basic information. I’ll get back to you if I can remember it…
The other guy you want to look at is Jonathan Riley-Smith, who’s done all sorts of introductions on the topic of Crusades, and is very well-respected in the field. I’ve used a variety of his articles in my research (on specialist topics), so I don’t have any particular books to recommend, but he does a very good job and can give a wide range of useful perspectives.
Hm. The rest of what we looked at were primary sources, so if you wanted to get into those, you’re straying from the ‘most efficient’ route into the more in-depth and certainly very valuable but time consuming (sometimes) and often confusing route; if you would be interested in reading some of the original documents, I’d be happy to elaborate, but they’re something which are, for the beginner (by which I mean up through college even) best covered in class—they’re often very hard to reconcile with one another and can be very confusing and unhelpful without a guided examination. This is particularly true of the Crusades—I don’t know how many charts we drew up comparing and contrasting the various accounts of this or that event!
What exactly are you looking for when you say the ‘British Monarchy’? Are you just looking for info about particular queens and kings, or more on the evolution of the institution itself? Either way, I’ll have to go back and dig through my books to find anything good; we’re out of my speciality here :) Same goes for French Revolution; I’ve only covered it inicdentally myself, but I think I can find something useful if I review a bit.
Excuse my for straying outside of matieral you might actually want, given your purposes. I blame my seminar for my over-detailed ramblings!