You are wise to check on their noise levels, because with the quantities you will be using the system could get fairly noisy. IMO you do NOT need high rpm fans.
As mentioned before, right on the outer body of the fan, there will be small arrows [usually molded and raised], one parallel to the fans major surface, that is the direction that the fan will rotate [you cannot change that]. There will also be an arrow perpendicular to the case that shows the direction of the airflow. [not being nasty, but if you want to have the air flow from outside the case to the inside, you mount the fan so that the arrow points inward]
The side fan is likely to be powered from the standard four pin Molex connectors [the standard things that the Power Supply will have a lot of] so why not buy that fan and have it to look at.
Now, understand that there may be some fans that you would prefer to plug into the connectors on the mobo, for these you must first know if the mobo connector is 2 pin or 3 pin, and buy a fan with the connectors to match. Thus for additional fans wait until you select your mobo, see how many fan connectors it has on it [there will be at least two], one for the CPU/HSF and one noted as system fan [this designation really is not meaningful] to use for the fan of your choice.
The Molex connector is much larger than the 2 pin and 3 pin connectors. The 3 pin on the mobo are from a chip that adjusts the fan speed based on the temperature it detects. The 2 pin adjust the speed similarly, but uses a different method to set the speed.
You can also buy fans that use the large 4 pin Molex, that have a temp sensor on them to detect the temp and control the fan, or a version that has a small variable resistor that you can manually adjust to set the speed.
Youy should go to http://www.cyberguys.com, and get them to send you a catalog, then you'll be able to see pictures of all of these options.
They also sell adapters to adapt any type of fan connector to any other type. They also sell Molex Y cables if you need to add another four pin connector for anything.
Now for the Power Supply, many of them have two fans, both exhaust, you have no choice. Usually the one on the rear that you see from the outside of the case runs directly from 12 volts from inside the PS. The other one is usually a temp controlled one that is intended to plug into a mobo 3 pin connector, so that it only runs when the temp gets above some point.
Keep in mind that all of these fans consume finite amounts of power, thus the power supply has to provide power to all of them. Just building up to not skimping on the wattage rating and quality of the power Supply.
A sleeve bearing [also called a bushing] is simply a piece of Brass or?? with a precise size hole that the shaft of the fan goes through to get supported. The brass will eventually wear enough so that the fan will wobble and have to be replaced.
I have to assume that you know what ball bearings are, roller skates, automobiles etc . The metal ring that the fan shaft goes through for support is ringed by hardened steel ballsfor a full 360 degrees. then there is also an outer ring surrounding the balls. Both the inner ring and outer ring have a "race" with is a hardened steel precision cupped track that keeps the balls in line. With ball bearing the shaft rotation has far less friction and thus less wear, and thus longer life, but alas, they also can fail.
A one ball bearing fan has the shaft supported on one side of the blades only by a ball bearing. Cantilevered but only a virtually zero length cantilever. A tow ball fan has a ball bearing on each side of the blades and is thus a more balanced shaft support.
The bane of the modern computer is that the CPU's now consume so much power, which is all converted to heat and thus the need for fans to keep them cooled. Thus a new reason to have to open computers has evolved. The first was the battery for the CMOS which has a finite life. An all solid state computer could probably run 20 years, be sealed and thrown away when it failed. No more, now one should understand everything that is in the computer, and by building your own you are well on the way to being able to care for your system with ease.
Solid state circuitry has extremely long life many, many years, however fans and other electro mecanical things have much shorter life. Where one could allow earlier computers to run for years, it is not unusual for a newer one to have a fan fail within 2 years.
You'll go nuts selecting the mobo, the CPU, and the Video. The technology chances faster than we can make a decision what to buy.
I cut my teeth on vacuum tube technology, and can really appreciate the fantastic advances. A vacuum tube computer occupied huge rooms and probably failed every couple of hours, thus requiring constant maintenance. LOL