Need Guidance

[imranali_2004us]

I am currently on Tier 2 General Visa and my job contract with Recent employer will end on 2nd August-2016 and Tier 2 Visa expires in September-2016 with my recent employer.I have got a job offer from new employer and I will be starting from 21st September-2016.My COS with the new employer will have the same start date of 21st September.I have few queries,if anyone can help me with that,I will be really grateful :

1. I have asked my new employer to issue me the COS after 21st June-2016 as it will be three months before my joining date with them,is that right?

2.Can I immediately apply to switch my tier 2 Visa to the new employer after issuance of COS after 21st June-2016 as I will be still working with my current employer until 2nd August-2016?

3.I am planning to travel outside of UK after 2nd August-2016 and return on 21st September-2016,will UKBA question me for the gap from 2nd August-2016 to 21st September-2016?

4.When should I apply for visa for my wife,should I do it now or should I come back and join new employer on 21st September and then apply?

5.Is it safe for me to have the gap from 2nd August-2016 to 21st September-2016,or should I join my new employer immediately after the end of contract with my recent employer?

6.How long I can stay in UK after my contract ends,can I stay in UK until the expiry of my Tier2 Visa? Also Can I work for my recent employer for the whole month of AUGUST?