I started with a Jedi on the light side, i hear the Dark side is fun and the story interesting. the one negative i hit was I tried to be a tank and it was just too much work and punishing..so a Sentinel should be a good choice, the bosses are tough at each general level as you advance but if you have skills in combat i am sure you will do fine.
Re the Saber, you level up and have access to limited weapons at the start and then they improve over time, along with the equipment, there is a huge range of equipment you can buy or find or loot, i dont want to spoil your discovery of the way things work but you will have a chance to try out a lot of equipment as you progress. Others are much more knowledgable about this, but that is my response to your question about that.
You gain, have to pay for, skills to allow you to weild the two sabres and the double blade so you should start gathering credits in the learning area right away as the skills are expensive in the in game currency. You will pick up on it soon i am sure, and anyone here will help they were very helpful to me. I wont be back in the game myself until Monday or so but if i do see you i will say hi..and help if i can. Be sure to post your avatar name and i would suggest joining one of our guilds they are a lot of fun and you will need to do group activities to advance past things....there is a lot you can do SP but you will need help at some points and people here are great...
It is a really remarkable game world and a lot of fun and it does expand our chance to see the Star Wars universe a lot. The in game videos and movies are superb and they managed to almost seamlessly match the game vids and the actual game graphics so it feels very realistic. I am just coming back after about six months away so i will have to remember a lot too.
There are special data chrons hidden around the world that give special abilities and game story but they are hard to find. They give off a glow you can see as you explore..if you see a coloured glow on some high ledge or place that is usually a data chron, there are several at least in each world.
Here is what they look like in the game...
they are hidden, often very well, inside too..
If i got something wrong hopefully some of the "elders" will correct me, i just wanted to welcome you and encourage you as you wait for the download, it takes time and there was a recent patch too that will load up, 1.5 i think it is. they are fixing things all the time and adding new content and new events.