Can I sell my part or borrow on my 1/2 of the value of the property?

You cannot encumber half of a property with a loan, so you would need the consent of the other owner. You can sell your interest in theory, but in practice only a fool would buy into a partial interest.

Certainly, but no one is going to give you much. Since your brother lives there rent free [as could you], it would be difficult for a buyer to be able to rent the house and your brother would be entitled to half the rent [it is half his house]. No one will lend you money because it is very costly to try to force the house to be sold.

Theoretically, yes. As a practical matter, however, you will have a problem finding a lender or buyer. Your remedy is to file a partition action and get a judgment for sale. You'll need a lawyer for this. You can get a referral from your local bar association.