A "power of attorney" authorizes you to legally make decisions on behalf of your father when he does not have capacity to manage his own financial affairs. The power of attorney document itself usually specifies the extent and nature of powers it provides, including authority over banking, real estate matters, stock, etc. This legal authority is only as a "fiduciary", all of your assets must be used to provide for your father's welfare. It takes work to properly manage someone's affairs and this commonly only done as between family members. If your other family members are also elderly it might make sense for them to grant powers of attorney to someone they trust (who will take this responsibility seriously and properly). The alternative is a conservatorship which is a court-supervised process and it requires the conservator to report to the court regularly. In some ways this power is similar to an "attorney" in the sense that you're acting on behalf of someone for their interest, but not in the common way we use that term as someone who goes out and files lawsuits or advices people on their legal rights.
The terminology used is sometimes confusing. A Power of Attorney does not make you an "attorney" for the person, nor does it give you the powers of an attorney. What it does is allow you to step into the shoes of the (generally) incapacitated person and to act as their agent.
You generally have the same rights and powers as a guardian or conservator would have, only there is no court proceeding and no court authority to back you up. Nevertheless, most people and companies treat you in the same way as they would your father. You are required under the law to act in HIS best interests, and you can get into trouble if you do not keep records of what you have done and keep your father's business separate from your own. Having said that, your father's liabilities are his own, and you do not incur any personal liability for his debts.
Whether or not you need a real estate attorney depends on what you are trying to accomplish. If you are selling real estate and it is something your father probably would have hired an attorney to assist with, then you will want to consider doing the same. More information is needed before I can make any suggestions to you on that aspect of your summary. Please feel free to contact me if you have additional questions or concerns.
I recommend you talk to an attorney who focuses on estate planning, because there are other issues beyond just selling property. Whenever you are trying to manage an on-going business, special powers should be specified in the power of attorney that are not contained in general, vanilla-flavor form. Also, title companies are now requiring special powers of attorney with specific powers related to the sale, including description of the specific property. It is often necessary to have more than one power of attorney - each taylored to a specific purpose, or you can incorporate it all in one document. It is best to review this with an experienced estate planning attorney in your jurisdiction.
Yes, you need an attorney with experience in all three areas: real estate, business and estate planning.
The attorney will have to examine the documents and meet with you to get an overall picture of what was intended by your father, and how you can carry out his wishes for his benefit.
The experienced attorney can also advise whether additional documentation is needed, and whether court approval would be necessary or advisable, taking into account your father's competency.
To the extent you are acting properly as your father's agent, attorney fees would be chargeable to your father and his business or estate, not to you personally.
The final reason you need an attorney: to avoid violating any of your fiduciary duties and being found personally liable to your father, his creditors or his heirs or beneficiaries.