Thank you for your question.
What you are asking to do is possible, but you're talking about two separate documents, actually (three if you include the DNR).
For your brother to be able to pay your bills should you become unable to do so (e.g., you end up in a coma, for example), you would want a "Durable" Power of Attorney, which gives the person authority to do things such as pay your bills, , deposit checks into your bank accounts, file your taxes, etc. A "durable" power of attorney simply means that it is valid through your period of incapacity, and only terminates either when you are competent and revoke it, or you pass away.
Putting his name on your bank accounts would generally be less favored, because by doing so, when you pass away, he would automatically be the owner of the account, which may or may not be your intention. Additionally, if you make him a joint owner now, he could theoretically take all of the money out of the account and spend it, without consequence, because he would have just as much right as you to the money.
For your cousin to make medical decisions for you if you are not compentent to do so, you need to get a Medical Power of Attorney, also called a "Health Care Surrogate", or "Durable Power of Attorney for Health Care." This document is not combined with a Power of Attorney for financial affairs.
A DNR is not something a lawyer would prepare. That is something you would want to discuss with your doctor and mention that you would like in your medical file. Additionally, it is standard procedure that when you enter a hospital (assuming you are competent) for a procedure, they will ask you each time if you want a DNR.Here
is a Durable Power of Attorney for Health Care Decisions from Iowa Legal Aid you can fill out. Here
is a Durable Power of Attorney for Property/Finances. I've also found this one
Note that you do still need to have these executed in front of a notary.