Tier 2 General Extension-CoS Work Dates: Start and End Dates

Hi,
I am planning to apply for Tier 2 General Extension visa. Please find my current Visa / CoS details followed by my queries regarding Tier 2 General Extension. Can anyone advise on my queries please

Information:

** Passport Validity:
Issue Date: 28 December 2007
Expiry Date:27 December 2017

**Current CoS Details:
-Current Visa Status: Tier 2 General
-Work dates:
Start date: 16 December 2012
End date: 15 December 2015
-Visa Valid till 29 December 2015
-Job type: 2132 IT, software professionals

**New CoS Assigned with SAME Sponsor (A Rated) and SAME Job:

-Tier and Category: Tier 2 (General - Extensions)
-Current certificate status: ASSIGNED
-Current certificate status date: 02 November 2015
-Date assigned: 02 November 2015
-Expiry date (use by): 03 February 2016
-Work dates
-Start date: 02 November 2015
-End date: 01 November 2016

-Job type: 2139 Information technology and telecommunications professionals not elsewhere classified
(Note: 2132 is now changed to 2139, source: Standard Occupational Classification (SOC) Codes 6 April 2015, Version 04/15)

-Tick to confirm the sponsor certifies maintenance for the migrant: N


Queries:

1. As I am applying for Tier 2 General extension (with the same sponsor and same job), is it REQUIRED to show proof for Maintenance of funds for me and my wife?

2. If the answer for query 1 is YES (I hope not), will I meet the criteria if my sponsor certifies it on the CoS ('Tick to confirm the sponsor certifies maintenance for the migrant' to Y)? And will this cover both of us (me and my wife)?

3. As my current Passport is only Valid until 27 December 2017, will this restrict me to get my visa approved for three years, until 2018? (if my sponsor gave the work start and end dates for 3 years i.e. Start Date - 16 December 2015 and End Date - 15 December 2018)?

4. New CoS Assigned - The Work End Date given on my current CoS is 15 December 2015. However, in my NEW CoS, the work dates given are prior to the current work end date and visa validity date (Start date: 02 November 2015, End date: 01 November 2016). This did not make any sense to me. Is this VALID?? If I apply for my extension with these dates, will it be a approved??

(I have raised my query with my HR about the work dates given on the new CoS assigned, they will get back to me soon and I am planning to request my HR to assign a NEW CoS with new work dates)

Your help is much appreciated, thank you.

Hello,

How did your extension go? Did you change your Work Start Date? Can the work start date be before the current work end date?

Thanks