If I convert to H1B1 (I'm Singaporean) from H4 do I have to go back to Singapore for visa interview?I'm currently in US.

Yes there is a minimum wage depending on location and position. You only need to apply for the visa stamp if you travel internationally. More...

Am I allowed to work based on the receipt and before receiving the actual work authorization ?

You do not have valid work authorization until you receive the EAD document.

Travelling to USA on b1/b2 with I 130 filed?

No, do not voluntarily disclose anything, wait to be asked questions and then answer truthful short answers responding only to the questions asked.

Appeal a case while overstating my visa less than 6 months.

Regarding your immigration question, you should leave before you trigger the 3/10 year bar. Can't tell what your situation is based on your facts,...

Does Disability ( hard of hearing), in this case US citizen make marriage interview difficult with USCIS?

I don't see why this would be an issue, they can always ask questions in writing if she doesn't understand.

How can I sue DHS for hurting me emotionally for pending my I-130 petition for my wife for 3 years under security check ?

I suppose you could sue them but it will cost money and it not likely to succeed. If you haven't talked to an immigration lawyer about your case...

Tell them you made a mistake on the day of the interview and give them the correct information.

Can my H4 port of entry be different from my husband's H1B port of entry?

Yes, the SEA is fine, doesn't matter.

How should I do if employer force me to pay all a E2 Visa expense after I quit a job?

If you signed a contract agreeing to pay for the visa fees if you left the company before a certain date, then you are liable for at least some of...

You cannot legally work until you have a valid EAD card. Doesn't matter how you ask this question, the answer is still the same.