Great to see someone start a Chaos army!
Having started almost the same way, here are some of my thoughts:
- The Chosen , in theory pack a good amount of punch against most things once they get into close combat. Unfortunately this is usually quite obvious to your opponent and he will start shooting them to bits before they do arrive.
My advice would be to put them in some kind of transport and more importantly add a few more marines without special weapons to soak up the inevitable casualties the squad will sustain.
- Your opponent will know, what the murder sword does. Either he will also be a beginning player in which case it is only fair to tell each other about the special rules in your armies, or he will have more experience and will know of his own accord. In either case, people are rightfully terrified of the Murder sword and will either constantly run away from it or focus fire it to death, wasting your precious points.
Your Murder Sword definitely needs a way to get around fast, be it via reliable transport (and that's not a Rhino!), jetpack or bike.
- Each of your machines of war is a fine choice on its own. Bear in mind however, that all of them are AV12, which can be taken down by a single lucky hit with a missile launcher or similar. If you are looking for heavy weapons, you might consider replacing one of them with Havocs , who will get more heavy weapons for less points or a Predator, which is slightly more durable.
- Try to have some units that pose enough of a threat to be worth shooting at, yet can take a bit of a beating. Simple Chaos Space Marines with maybe a special weapon or two are great for this. Remember that your opponent will be killing your troops as well, so make sure you have something that you won't mind losing too much.
- By all means keep those cultists. They are cheap and annoying. You've got exactly the right idea on how to use them. They will do something useful in most games.
Having said all that, (and I do hope this wasn't to harsh) you have a fun starter army. Just find a few like-minded players and have a go. The best way to find out what works and what doesn't is to just start playing and having a blast.
Glory to the Dark Gods!