File for an estate, collect the money and pay yourself back.

Next to zero. It is nearly impossible to revoke a signed waiver.

Depends on the terms of the trust and your aunt's power as trustee.

If you sign the form, you will have removed yourself. If you do not, based on your post, you should not be removed. The decedent's choice of...

The insurance company. You do not pay it. Tax liens run with the land, and land is not yours.

As administrator you can sell the house. What issues and any restrictions that exist depend on the terms of the letters you received.

That is the correct result. It is an even split.

If you are a joint lessee of the box, the cheapest and easiest thing is for you to fly to NY and open the box. The legal fees to do anything else...

This is no problem. If there is a lawyer on the other side, start by asking them. If they refuse, or you cannot reach them, call the judge's...

You will need what is called a voluntary administration. It costs $1, and you can do it yourself. Call the Suffolk County Surrogates Court.