A deed of transfer for natural love and affection is the simplest way. All deeds must be in consideration of some value, but if you put monetary value on it, then the fees and liabilities increase. The deed would have to be presented to the revenue commissioners for stamping but as this would be a "valueless" transaction, they would stamp it exempt. Such transactions are now carried out through e-stamping...
My advice would be to talk to a solicitor based in a large city, where conveyancing might be their key business, smaller one stop shops sometimes are not very good with conveyancing.
If you are not in receipt of rental income, then you cannot be taxed on it, your brother would be entitled to a certain level of rental income before tax would kick in.
Good Luck