I would say you need some kind of contract or binder which outlines all the contingencies and closing date. Depends on the state where you live as to how you should handle the rest. In some states a realtor on a fee basis might be fine. In other states you might want to hire a real estate attorney to handle your transaction. It just depends.

Just an FYI..banks do not require a home inspection. However, most do require a termite/wood destroying insect inspection...and treatment on the sellers dime if evidence of wood destroying insects is found.

You definitely should use a real estate attorney to protect your interests, especially as you are unfamiliar with the process.

You need a written contract to sell real property.

You can negotiate till you are blue in the face verbally and back and forth in writing, but under the statute of frauds ALL sales of real property MUST be in writing and signed by all involved parties.

You could use an RE agent (they will have access to a 'standard contrast' to start from, or pay an attorney to create a contract (they will use a standard from also) and later as required.

There are a handful of federal and state laws you must comply with, like lead notices to the buyers and such.

A good RE attorney should know about them, but every RE agent knows what is required in their state for required notices.

'Help u Sell' and others like them charge a percentage fee.They will help you with all paperwork etc.
Expect to pay around 5K.

There is no reason to hire a RE agent when you already have a buyer. An attorney is the way to go here.