1. You cannot extend a visa outside the UK. It will be a new entry clearance visa. Has your previous ICT visa already expired? Presumably you are still working for the same company in your home country?
2. Are they a licensed HO sponsor on the approved sponsor list? You are subject to the 12 month cooling off period before you can apply for a Tier 2 General visa. A sponsor will also have to conduct the full and proper RLMT before you can be offered a job and issued a CoS.
3.
Tier 2 Sponsor List (click)
4. A shortage occupation and a salary in excess of £155k might waive the cooling off period.