RainyCat, you can save SOME time by taking your stock part of the way in a pressure cooker, BUT flavors do NOT blend as fully under pressure, and you will never get the concentration of flavors that a true stock will give you if you stop at taking the lid off the pressure cooker. That will produce beef soup, not beef stock. So after you safely remove the pressure cooker lid continue simmering the soup until it reduces (concentrates flavors) and then do the straining routine. How long you will need to reduce the soup to stock depends on the size of your pressure cooker.
As for cloudiness, it doesn’t matter how you make the stock (pressure cooker or the classic 2 or 3 days with a huge stock pot), at some point you MUST strain it through cheese cloth and/ or one of these:
http://tinyurl.com/ppbdkya
I actually use both at the same time, lining the stock strainer with the cheesecloth. And I buy my “culinary cheese cloth” on amazon.com too.
I’ve also found that freezing my GREATLY reduced stock in small plastic cups with lids REALLY extends their freezer “shelf life.”

I don’t know if you’re intention is to go “all the way” with a stock that has flour in it (often introduced along the way as an espagnole sauce, which contains flour) but if you omit ALL flour along the way, you will have a whoooole lot less of straining and filtering to do to get a “clean” stock. A LOT less… God knows how large Escoffier’s kitchen staff was, but mine is me and my housekeeper, and she is (literally) from Siberia, and doesn’t much like to cook, or eat for that matter.
And she ends up with me, poor baby!
Anyway, in the photograph of the little cups they are filled to the exact perfect level to cap, refrigerate until well gelled, then pop in a quart (or larger) zip lock bag and stash them in the freezer. The old freeze your stock as ice cubes then store them loose in a ziplock bag ends up with a far shorter freezer life because the air in the bag allows ice crystals to form on the frozen stock, and that will kill the flavor of the stock pretty quickly. Been there, done that, got yucky tasting stock! Yay cups!
Relax and have fun. Beef stock – even the classic Escoffier kind, is not that hard. It just takes time. So relax and have fun!
Sheesh! I started this hours ago. Computer problems!