If you're starting a business, I wouldn't take on any debt if I didn't have to. It seems everywhere the economy is tight. People aren't spending more than they have to.
If things are different in your area, your pipeline is full and you've got work lined up as far as you can see into the future, then it's time to start talking to the dealer.
It's not possible to tell you what you need to charge without knowing what your expenses are. Charge enough to cover your expenses and to make a little profit.
As far as what type of work, a skid steer is a tool that can be used for many different things.
Think about what kind of jobs you want to do and try to market yourself. Most customers will hire you to complete a task, not operate a machine. Think about that when assigning a value to a machine (both for billing and buying purposes). You will not be in competition with other contractors offering "skid steer services". You will be in competition with anyone and everyone who can complete the job per the customers' demands whether they own a machine or have a different way to get the job done. Keep your overhead lower then the competition's and you might succeed.
Personally, if it were me, I'd give it a shot with the equipment that you already have.