US Immigration from Uruguay

Hi all, been a while. Just wanted to double check and make sure I'm looking at these actions with my Husband to be sure we're submitting it on date/correct time.

My Husband's conditional green card expire on 8/19/22.
If I'm reading this right, to submit the I-751 form within 90 days from expiration date as on May 21, 2022. If so, I'll hop on the I-751 May 2022 train topic.

Additionally, to submit the N-400 will be on July 15, 2022. We got married in July 15, 2019 Thru K-1 Visa. I don't know if there is a N-400 train topic or not, didn't look yet lol.

If not correct, please update me on how it wasn't and how could I look for more accurate timing and structures to take. Thank you very much VJ.

Is anyone facing delays in the approval of the I-829 (removal of condition on Investor immigrant EB-5)

I am a US citizen over 21 years of age. Can I petition my sibling (who is currently 15 years old) via I-130? I know it's faster if my parents immigrate but they are not interested in doing so. I realize my sibling will have to wait 10+ years and I'm fine with that. I'm just wondering if he has to be of a certain age for me to be able to file a I-130 on his behalf? Also, must he remain unmarried the entire waiting period?