Tier 4 Dependant considered for Tier 2 Sponsorship

Hello,
Please I need urgent advise here

I am a Tier 4 dependant and I have been offered to be sponsored for Tier 2

However, my spouse Tier 4 Visa expires by May 30th

Because of the short notice, my sponsor requires that I get extension for my spouse Tier 4 to allow time to process my Tier 2 Visa.

I am considering registering her for ACCA

I need advise on how to go about this;

If ACCA Tier 4 cover for dependant?
If ACCA Tier 4 allow dependant to work full time?
If it is possible to switch from ACCA Tier 4 back to Tier 2?
What is the implication of switching from ACCA Tier 4 dependant to Tier 2 within a month?

I will appreciate urgent response please (Visa expires May 30th)

Thank you