Paying taxes while residing out of the country

Hello, 

I have several questions to ask. So hopefully I can get them all answered. I am a citizen of the United States. However I do not live there anymore. I live out of the country but I work for a company in the US. Here are my questions:

#1 How do I file my taxes at the end of the year? I know that I still have to pay federal, but what about state taxes? I last resided in the state of Maryland and I use my family's residence in Maryland to give to my employer. However, I do not reside there. Do I still have to pay taxes to the state?

#2 I'm an independent contractor, and I will get a 1099 at the end of the year. How will this affect me also because I live out of the country?

# 3 Instead of making multiple quarterly payments to the IRS for taxes, can I pay a lump sum at the end of the year or does that put me in jeopardy when I file?

Thank you for all of your help!