Welcome to the fold!
I would do as others have recommended and try to keep it as an 'in-person' event if you can. That is what makes the game so much fun, the personal interaction. I know that for awhile all my friends and I would just gather in (insert MMORPG of choice) and play as a group but it didn't take long for us to realize it was not even close to being together and throwing dice.
Being a DM takes time and practice. You are the story teller that takes the characters through the adventure, giving descriptions and playing the parts of the people/monsters they meet. Take the time to prepare before a gaming session to cover what part of the adventure your party will be going through and just try to have fun. A little bit of preparation will keep the game flowing and keep it from coming to a halt every few minutes. Being a DM can be a lot of work but it will also be very rewarding and a lot of fun.
My group meets every other weekend on Saturday afternoon and (wife permitting of course

) we usually play for about 5-6 hours. Of course when I was your age (damn I feel old saying that Hehehe) we used to have all weekend sessions that were just incredible! Again, this was before computer gaming was really widespread. I would prefer it every weekend as it is easier to keep the flow of the story/adventure but it works out good for us as is.
I will also agree that Minis are NOT a requirement and can always be added later. Some think that minis just slow the game down and turn it into a hybrid wargame. Just be descriptive during the combat encounters but it doesn't have to be exact. In fact not using minis will hel p you in the beginning as it will force you to describe things in more detail since it will have to be pictured in everyone's mind instead of layed out on the table top.
Also as has been posted there is a LOT of free adventure material out there to be had. Check out some of the links that others have posted and you can save a few $$ and get some really cool adventures that you can run as is or just take what you like from some and make up your own.
Ok, enough rambling.

Welcome again, good luck and just have fun!
-Brund the Long Winded