B Visa

1. I am on H1B VISA and was notified that my employment will end on January 20th. I am actively seeking new job opportunities. Can you please let me know what happens if I am still interviewing after 60 days and become out of status? 
2. Do I have any other options to change my VISA status before/after my employment is terminated and I fail to secure a job before the 60-day period is over? 
3. Does my VISA become invalid after the 60 days or can I still find a job and reactivate it if I get an offer after the 60-days?

Have any rules changed regarding getting a spouse visa through H1, L1, or O1? Also is traveling on a tourist visa to the US after marriage not ok, with a pending GC application? Finally, does the US have any special agreements with the UK, EU, Singapore, Dubai or Australia for visas that may qualify in this scenario?

Parents came to the USA on a B-2 Visa in March 2021. I have requested an I-539 extension in August 2021 due to COVID and they stayed till Jan 2022. Eventually the extension got denied. Is this a problem?
 

We live in Delaware. We had extended my parent's B2 Visa twice in the past. Once in 2016 and it was approved. Second time in 2018, but they went back to India before the decision on extension. For the second extension, we got a letter from USCIS stating, "Since they left the country, USCIS is not approving the extension, However they can travel again"

Again in 2019, they came and left the US in 6 months.

This year, they came last week on Jan 31 2022, but CBP in Philadelphia airport took them for inspection at the port of entry. After a long wait time, CBP came back and told them that they had overstayed and they had canceled their B2 Visa. CBP gave a letter that they can stay for three months and leave the country before April 30.

Though we followed the process defined, we are really not sure why they canceled the visa.

With this situation, Can you please advise what is our option,

1. Can we appeal for visa reinstatement?

2. Can we go back to the country and apply for a B2 Visa again in May ? Or should we wait for some time before applying again?

My parents have been here on visitor's visas since the beginning of August. If they are here for the entire six months, can they come back again within six months of leaving the U.S.?