Sleeve bearing is a rod in a hole. Think high-tech version of a Conestoga wagon wheel. The lubrication is in the grease. You should lubricate each sleeve bearing fan before you install it, and re-lube it periodically as you would your car. See my sig for how.
A sleeve bearing tends to slip along its rotational axis so that placing it with airflow directed upward usually causes problems.
Fluid dynamic bearing is a sealed sleeve bearing which may or may not have better axial stability, so you ought to be able to point its airflow up. But not all of these "long life bearings" and other variations can have their airflow pointed up.
Ball bearing fans:
1B1S - a single ball bearing race and a sleeve bearing. I think I've run into one. It acted like a 2BB, but in theory one side will wear out eventually and leave you with an unstable fan.
2BB - double ball bearing. Ball bearing race on each end of the shaft. Best for durability but can add a bit of extra noise which you young dudes can hear. Best to lubricate these before you put them to work. These can point in any direction, no sweat.
Best combo for quietude: get as large a diameter fan as you can, go with moderate to low rpm's. Larger fans push the same cfm at lower rpm.
So: TY-140 is inexpensive, PWM, relatively high static pressure. Very quiet, good cfm. Good roundup here
. I use one as a top intake fan, hooked up with my cpu fans so that when my cpu fans go from idle to full speed, so does the case fan that feeds them.
TB Silence does not push much air but it is quiet. See item 4 in my sig, chapter 1.
Kaze Maru 2 (Slip Stream 140) is excellent at 800 rpm and 1200 rpm, the two speeds I have tested (item 4 chapter 4 and item 4 chapter 5, soon to be published). The KM2's and TY-140 are good fans for case use because they have 120mm screw hole spacing. So, for example, I have a KM2 on my side panel. It fills up 100% of the 120x120mm space with little left over, where a 120mm fan fills less than 78% of the 120x120mm space.
Put a 140mm fan in your 5.25 bay (see my sig). Adds flow-through.
If you can, cut out your rear grill and leave the back opening and all of your backplane slots uncovered. I have six filtered intake fans and no exhaust fans, for example. Because I use filters I use Gentle Typhoons for all my 120mm fan positions - better static pressure. But Slip Streams are inexpensive; just keep them lubed and don't use them when air must go up, as in bottom intakes.
Whew. Hope that's enough.Edited by ehume - 10/17/11 at 6:23pm