Patch cables are for connecting endstations into the cabling system (PC->Jack, Switch/Router/etc--> panel). Since they can potentially see a lot of flexion, they are made with stranded cable.
The cables in the wall don't move much, they're made with solid-conductor wire. Solid has better transmission characteristics.
A standard EIA/TIA structured cabling installation is such that the signal can travel 100 meters intact. Of the 100 meters, 90 meters should be solid conductor cabling, and five meters at each end can be stranded (jumpers).
I believe the specification allows for two intermediate cross-connects (punches or panels) as well.
The "Category" specification usually refers to Unshielded Twisted Pair (UTP), but is also appropriate for shielded cables. "Shielded UTP (read "Shielded Unshielded Twisted Pair") is usually referred to as "Screened" UTP.
If a cable is certified to a "Category" specification, that means it meets some EIA/TIA (the official body governing the specification) basic standard. The standard covers things like loss (attenuation), crosstalk (both near-end and far-end) and a bunch of other specs.
The reference to the number of twists is not entirely correct: It's not that the pairs are twisted MORE, it's that they're twisted at DIFFERENT RATES pair-to-pair (like, the orange pair probably has more twists than the brown pair). Since the cable manufacturers know what application is likely to use wich pairs, they can optimize the function on a pair-by-pair basis (like: Ethernet over UTP uses the conductors at 1& 2 and 3&6 (pair two and pair three). THIS IS WHY IT'S CRITICAL TO USE THE CORRECT PAIR ORDER FOR THE APPLICATION....using the right pair order means the application is using the pairs OPTIMIZED for that specific application.
The pair order for EIA/TIA 568B is: Orange-White, Orange, Green-White, Blue, Blue-White, Green, Brown-White, Brown (with the open end of the connector towards you, with the clip down. The EIA/TIA 568A ordering swaps the orange and green pair. So, if Ethernet uses 1&2 and 3&6, the signals should be on the orange and green pair. (Pair one is blue, pair two is green, pair three is orange, pair four is brown (568b, for 568a, exchange the orange and green).
So, there ya go. I hope this helps to understand the most important part of your network. The fastest machines won't communicate worth a squat if the cabling is not done properly.
FWIW
Scott