Takolana

It seems you are suggesting trying to deceive CBP when you enter by showing them proof of a job you no longer have and showing them a return ticket you plan to change.  This is not a good plan. 

I doubt he's exempt from the public charge ground of inadmissibility, therefore no fee waiver is available for the I-485.

Thank you so much!! I will not file for it I just needed clarification. 
No he is not I just wanted to know about it 

Thank you for replying. I mean do we have to file for the green card within the 90 days they gave us or can we wait? We do have a joint sponsor, but it states I can file for it if I am on "means-tested benefit"( I am a full time college student).  

Thank you so much!! I will not file for it I just needed clarification. 
No he is not I just wanted to know about it 

K1 is a single entry visa good for 90 days so as long as you marry and file within the 90 days you can wait.
 
Do you have a joint sponsor?
 
Have you read who is eligible for a fee waiver?

Most people add their spouses to an employer-based plan.  I recommend you look for a job offering health insurance.  Being on your parents' insurance as a married adult does not make sense.

health care .gov for health is affordable health care for anyone
 
u need ASAP to get to SS office and get him a number /needs to be done before u run out of time to get it and have to wait for AOS

You have to be a PR for 5 years before you are eligible for Medicaid

I didn't answer that part because I don't know the answer.  It appears (from reading the same website you pulled your screenshot from) that most immigrants have a 5 year waiting period before being eligible.  K-1 is included in the group that must wait 5 years.  That is 5 years from green card issue date, not 5 years from entry date.

Health insurance is not required for AOS or any other stage of the immigration process.  Health insurance statements are sometimes submitted as bona-fide marriage evidence when removing conditions, but it is not mandatory.  It was a requirement for a short period of time for certain immigrant categories from 2019 until 2021, but even that requirement has been lifted.