1- You're going to ask the court to award you money. How much depends on how badly the job was performed. You might try and get all you paid back but that rarely flies. Better to ask for a specific amount, somewhere less than 100% of what you paid the guy.
2- No, you don't need and shouldn't get a lawyer for Small Claims Court.
3- File in the Small Claims Court that has jurisdiction over the property where the work was performed.
The other advice given you in answer #1 is spot on. File your claim rapidly and document everything. Take multiple photos, get pertinent information from the web printed off, plus any correspondence you've had with the contractor, especially proof of payment(s) and any discussions you've had with him about the quality of the work.
Don't leave stuff at home thinking maybe you might need it later. Your day in court is your one chance to get it right. Make sure you have everything you need with you and readily available to show the judge if asked.
Finally, recognize that you're going to be in a legal proceeding which has its own rules. You will be given an opportunity to explain to the judge what the problem is. The contractor will also be given an equal opportunity to do the same. Don't interrupt if something said annoys you and don't show frustration, aggravation of anger. Keep calm and let the judge do his/her job.
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