1. I believe that when you get your box (CE/Delux), and you input the code in the website, after the 20th... your account will become CE/delux (depending on what you bought), and you should be able to get the extra items you purchased.
2. You get one at level 10, and second one at around level 20 (depending on how quickly you do main storyline), as to how many you'll have to wait and find out (should be more than 2 ). You should not be able to pass them up, but not sure about that.
3. They are 4 man heroics. You can do them with say 1 tank , 1 healer and 2 dps, or you can do it 2 people and 2 companions. They take about 30mins - 1 hour each, and drop heroic level gear for that specific level. First one is around 10-12, second one is 14-17, third one is 20-23 (around those levels). There are a few of them around. You get a bonus for doing one a day - bonus xp/credits.
Same story each time you do the same one thou
4. dont know about SI, I'm a warrior ><
5. You can marry companions, and flirt with NPCs. Send companions gifts, maybe you can marry R2d2 >< Not sure how it works, my companion doesn't like me enough yet !
Hope i helped