Hello!
My English is very bad, but maybe You understand me 
I build robot and now I must build head, this head must turn left, turn right, up and down.
head weight: 2 kg
neck height: 10-15 cm
What parts can I buy that build neck this head?
I think about:
Lynx Motion Base Rotate Kit (product code: RB-Lyn-211) and DDT-500 (RB-Sct - 131)
or
SPT-200 (RB-SCT-06)
What do You think about this parts? Can I build this neck ?
Your English is fine. The two pan systems you chose won’t be able to move the head back and forth much since they use small servos. You would need something stronger like:
SPG785A-BM Bottom Mount Gear Drive Pan System (3:1)
SPT400 Gear Drive Tilt System (3:1)
or
1x Lynxmotion Pan and Tilt Kit / Aluminium (No Servos)
1x HSR-5980SG Digital Robot Servo for the pan
1x HS-645MG Servo Motor for the tilt
You can use RB-Lyn-211 with the pan/tilt kit above to add rigidity.
ServoCity parts are not compatible with Lynxmotion brackets.