US Immigration from Brazil

Hi everyone,

I'm currently in the US visiting my (now) fianc e and I have a few questions about adjusting status as a B2 visitor. I know there are a lot of similar posts, but I got a bit anxious and information is never enough! Before that, a little bit of context:

I entered the US on May 2nd to attend to my (then) girlfriend's graduation and help her move from Florida to Pennsylvania for her master's degree. In the meantime, her younger siblings came from Brazil to live with her to go through high school here and finally go to college in 2 years. They're all Americans. Right now we're in Pennsylvania and circumstances have changed: Partner proposed to me and asked me to stay since I'm helping so much with organizing the house and things in general, she knew it would be difficult to take care of two teenagers, but it would be impossible without me at this point. Back in Brazil I still maintain a registered individual business for video post production (which I pay monthly taxes for) and my bank account. I say this not because I intend to work while adjusting (I do not), but as evidence. I don't have a car or a house to my name since I lived with my parents and we shared a car. That is exactly the same information I gave the CPB Agent (except for the engagement which is of course new): I told him I was visiting my girlfriend, he saw my printed email with date and address for the commencement, my business papers and invoice for recent jobs, and my ticket back.
So, to the questions:

1. It's the most obvious one, but I'd like to get it out of the way: AOS is avaliable in our situation or will they red-flag us for something?
2. I've read countless people saying that the 90-day rule doesn't exist, but lawyers still say it's a thing to be considered. Should we wait the 90 days or marry whenever we see fit?
3. We will be needing a sponsor since she didn't make the required income for last year's tax return, but is making now (so I hope that's a win). What additional documents will our sponsor be filling?
4. About her siblings: they didn't live here last year, so they're not declared as dependents for last year's taxes, but they're of course part of the situation now. Someone said they didn't need to be brought up since the process takes the last taxes into account, but I feel like this is lying by omission and I will not risk our future together for some stupid reason. How are we addressing this situation in our Forms? Is it as simples as increasing the household number?
5. Our relationship goes back to high school, so besides photos, what other evidences can we produce while I'm here in a visitor visa? (I'm being added to the apartment lease at the moment.)
6. Is there anything else we should know before going on with the process? Any tips?

To anyone who takes a minute to help, thanks a lot for your patience and time. I'll update things/answer back as soon as I can.

Hi, I have a doubt, if someone it's already in a I-130 process, it's possible for this same person apply for an EB3 visa process? The questions is: the same person can be at two different process at same time or as long the person apply for one process this person its not allowed to apply for another visa process, and I would like to know specifically about I-130 and EB3. Thank you in advance.

Hi! My case changed to the status "Ready" on 05/11, and I scheduled my interview and doctor. After that, I decided to ask the Consulate to confirm that they have my case there. They replied 3 business days later saying they received my case electronically, but were waiting for my file to arrive at their office, and hopefully I'd be able to maintain the date I scheduled my interview on.

Now I keep consulting my case on the CEAC's website every day just to be sure it's still with the "ready" status, and am waiting for the Consulate to tell me that my file is in their office.

Until monday, it was saying that the date that my case was "last updated" was 11-May (the same day it changed from In transit to Ready), but now that date changed to 25-May. Does anyone know what this updating date change means? Maybe they're reviewing my case at the Consulate?

Thank you.

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I was born with two last names, since I come from a country where that is common. One of them is from my mom, the other is from my father's mother. My father does not have that surname.

I never gave too much thought to that, until I got married this week in the US and the notary told us that my name would be seen as indicative of fraud. I would guess that the USCIS will assume that I previously got married to another person or something. However, my birth name is written on my birth certificate along with every single official document about me since then (e.g. my first passport, which I got at 14, before I could legally marry in my country). I have never been married before. My brother has the same last names that I do.

I was wondering, is there anything I can do? Will they just think that my birth certificate and previous passport are forged or something? Or can they verify that that is my birth name directly with my country's authorities?