Proof of bonafide marriage?

Submit sufficient proof to establish the bona fides of marriage. Letters and postcards are good other evidence of a shared life together such as...

Can u get a work authorization while waiting for a pending i-130 application filed by a sibling who is a US citizen ?

A sibling petition neither permits you to remain in the US not be employed in the US

Not sure what you do, however, a visitor is for a temporary time. Under your scenarios it may be possible, however, you will have difficult time...

Adjustment of Status on F3 category for me & my spouse.

Were you in status when you both filed. The interviews may be on different days.

Your status is not a criteria for the EB1.3 you must have been a manager or executive prior to entertain to the US for one out of the three years...

Adjusting of Status based on marriage ?

You may check processing times on the USCIS website. USCIS also publishes their expedite criteria on the website.

Will this affect future applications?

The US CIS and the US department of state share information.

Form I-485, item 8, #61 (Public assistance), is emergency Medicaid public assistance? is Obamacare public assistance?

If you are unsure better to reveal than conceal. Obamacare is insurance that is purchased so no.

How to withdraw an approved I-129R petition and would this withdrawal affect future petitions?

A denied application/petition cannot subsequently be withdrawn

The question asks for residence not ownership.