Change of employer and time off

[vavyr]

Hello,
I am currently in the UK on Tier 2 General issued in April 2017 for 3 years. Now I am looking to change my employer. The new employer will be applying for CoS most probably in May. I will be applying for visa most probably by mid May. The following are my questions -
1. Applying by say May 15th, when is the expected date I can hope to receive my Visa and BRP through non-premium channel?
2. Is premium processing advisable?
3. Is it possible to take a vacation and go outside the UK before I join the new employer? The new employer is quite flexible with the joining date. I have 2 months notice with the current employer(which I hope can be negotiated down if required). If this is possible then what is the time line looking like?
4. Is the following hypothetical timeline feasible from Visa perspective? -> Visa arrives end of May(say with premium processing), Resign on 1st June, Negotiate notice period down to 1 month. Last date at previous employer 1st July. Vacation of 1 month outside UK. Return UK 1st August and join the new employer immediately.
5. Another hypothetical timeline. Visa arrives end of May. Resign. Serve 2 months notice i.e. Jun, Jul. Take august off and join new employer on 1st September?
Thank you in advance and any help will be appreciated!

[CR001]

1. Applying by say May 15th, when is the expected date I can hope to receive my Visa and BRP through non-premium channel?

It can take up to 8 weeks, sometimes longer.

2. Is premium processing advisable?

It is your choice. Premium service does not guarantee you will get a decision on the day.

3. Is it possible to take a vacation and go outside the UK before I join the new employer? The new employer is quite flexible with the joining date. I have 2 months notice with the current employer(which I hope can be negotiated down if required). If this is possible then what is the time line looking like?

Should not be an issue.

[vavyr]

Much Appreciated @CR001

Can you also let me know if the application form needs to be made online?
I am looking at this information page - https://www.gov.uk/tier-2-general/extend-your-visa
There is the heading - "If you change your job"
But underneath, there are no links to start a new application. Should I presume this link as the start of new application? https://visas-immigration.service.gov.uk