Thank you for your more specific questions.
1) You have every right to hire this employee however you want to hire them. So you can make them a seasonal employee in the employment agreement and you can put a termination
date in the contract, stating that the contract ends on a particular date and that they will be terminated or offered full time employment at that time or may be offered additional seasonal employment.
2) You can hire any type of employee you want. You do not need special forms. As I said, employment in VA is considered "at will" and you can hire and fire for no reason or any reason at any time as long as you do not do so based only on the employee's age/race/sex/disability/national origin. There are no special forms or agreements necessary for this. Most at will employees are hired without any written forms at all.
3) You have other employees already, the forms do not change. You need to complete an I-9 employment verification (meaning you verify the person is not an illegal alien and has at least a visa for work) and a W-4
form for income taxes. You then notify the state unemployment
division and add them into your unemployment and you also have to make sure they are covered under your workers compensation
insurance as well. There are no other forms, you simply withhold the necessary taxes and you send them to the state/social security or wherever required, just like you do with your other employees.
4) Hourly employees must be paid overtime for all hours worked and time and one half for any time worked over 40 in one workweek. Only professional or management positions can be deemed exempt salary positions, meaning you can pay one flat salary to them no matter how many hours they work over 40 hours in a week. But for regular hourly employees, overtime is a must just like with your other employees.
5) You are not required to give ANY BENEFITS to an employee. You have to pay them and as a small employer you do not even have to provide health insurance.
6) No, the MD incentives are for hiring MD residents in MD. So if you hire them in VA there are no incentives from the state.
If they have child support issues and your company is served an order to garnish the employee's wages
, you must garnish them and send them to the child support collection agency. If you say they have a lot of other issues, you may want to consider not hiring them for those issues, since issues can bleed over into employee performance (late for work, calling off work etc). However that is the only liability you would face.