So very sorry to hear of your brother's situation. Prayers to you and your family.
Agree with the poster who said very few original death certs are required now. Most will take a scanned/faxed copy. Insurance company and maybe a bank would want an original. If the bank wants an original, take the original in and ask them to make a copy for their records and return original to you.
If your brother didn't have a will, the state has a will as a default. It's called dying "intestate" (meaning no will). You can get a copy (probably on line) or thru the county office where your brother is located. You might have to contact Austin, but I doubt it. The state's will, will likely say something to the effect that all property is split evenly between immediate family. (property does not include debt). The remaining estate will be responsible for any debts outstanding. All are negotiable.
I realize you might have a sense of urgency to settle the estate, and get it over with, but please take your time. You have over a year in many states to settle things. So there is no rush, and you can do more research to see what your options are for disposing of any assets you don't want, and draw out negotiations with debtors. But more importantly, it gives you more time to discover assets that are not readily visible.
Adjacent land owners are a good option for the sale of the real estate. I wouldn't tear down the house just yet. It might serve a purpose for animals for the new owner, and have value to him.
See if you can find a couple of your brother's tax returns. That would indicate any place where interest was paid to him (multiple banks, etc). Agree with the poster who suggested contacting the county for property tax info, which will disclose any liens on the land/house.
I bet with a little thought you can probably guess the password for his laptop. Pet's name, date of birth, "password", 1234, street address, girl friends name, old sweetheart, probably something simple. (maybe even your name)
And keep an eye open for the back up key for the safe. They usually look kind of funky.
Good luck, and God Bless your brother, you, and your family.