Based on CSPA, you should be fine. Consider a private consultation with an experienced immigration attorney.

Too complicated for a forum like this. it is advisable to privately consult with an experienced immigration attorney.

Your parent or sibling can petition for you. However, you probably cannot adjust status immediately since they are both priority-based visas....

Yes, an H1b holder can open a 529 college fund for his children.

I agree with the previous response. Try congressional assistance first.

It depends on additional factors. You'll likely need either a family or employer -sponsored application to obtain work authorization.

It is advisable to obtain a corrected I-20 to minimize any issues.

Yes, protect it with lamination if possible, and carry it with you.

Try emailing the embassy for technical assistance. I doubt you can change it directly on the portal.

You don't need to attend. You can contact USCIS and let them know to withdraw the petition. If you need to extend again, a new application will...