Employer willing to go through with EB3, have questions

hey all,

I've been in the US since I was 2, I'm 25 now and I came through an H4 visa (legal entry but parent's H1B expired and we overstayed -- they wanted a better life for me and any future kids). I've been on DACA since I was 15 and I earned a bachelor's degree in computer science and have been working at an employer for over 3 years now.

They are aware I am on DACA and are willing to go through the EB3 process. My questions are..

1. Will I have to leave the country for any step of the EB3 process?
2. If DACA ends, what will happen to the EB3 and can I ask my employer to sponsor for H1B?

2a. If H1B works out, Will I have to leave the country for any step of the H1B process?

-- keep in mind I had legal entry

As y'all can prob tell I'm terrified of leaving the country if there's even a slight possibility I won't be allowed back. This is my only home and idk what I would do out there (overseas btw)

update: I spoke to an attorney and got my answers

-marriage to USC = AOS in US, no need to leave since came in with H4

-EB3 = need to leave US for consular processing, however cannot be here undocumented for more than 6 months (if daca expires im screwed)

-H1B ‎ =  good option, will need to leave US for interview (but this approval will happen before I even leave the US so ill have a round trip ticket lol)