You go to the Sig website and watch their videos.... http://www.sigsauer.com/CustomerService/MaintenanceGuides.aspx
You must contact SIG to find out.
P239
No, the Sig P239 has a single stacked magazine, while the P229 has a double stacked magazine.
sig's website states MSRP is $800-$875. I see used from $550-$650 and new around $700.
Sig Sauer P229 and P239 chambered in .40 S&W. Here's the press release from Sig.
100-600 depending on specifics
50-400 usd
She usually uses the Sig P229 but in some occasions is carrying the P228 or P239
NCIS contract calls for over 2,000 pistols to replace the aging fleet of refurbished M11 (SIG P228) pistols purchased more than 15 years ago. The contract represents the first pistol procurement for NCIS agents since the agency's inception. The new P229 and P239 models will be chambered in .40S&W and fitted with SIG SAUER'S exclusive DAK trigger system. http://www.thefirearmblog.com/blog/2008/04/21/ncis-upgrading-to-sig-sauer-40-sw-p229-and-p239-pistols/
There isn't one. Most CIA employees will never see action, let alone have a need for a weapon. Field operatives POS (Procure on Site) to avoid arousing suspicion, and for deniability purposes.
To take it apart, verify that it is unloaded, lock the slide to the rear, push the take down lever down, ease the slide forward and remove the slide. Then take the guide rod and spring out, and then the barrel. At that point, you need a cleaning kit or cleaning supplies, so simply follow the directions on the product. Use gun products. Don't use motor oil or anything not specifically designed for a gun because some products can damage the gun.
Follow the instructions in the Browning BDA manual at the link below