Hello there! My son will be 1 in a couple weeks, so we went through all this pretty recently. Here is what I learned: It is best to buy a few different kinds of sippy cups. People told me that most babies like the Nuby ones, since they have a soft spout, almost like a nipple. My son was not crazy about these; he preferred the Gerber or Playtex ones that had a harder spout. Each baby is different, so buy a couple and see what one your son prefers. I still do not give my son juice, so don't worry about that. You can put pumped milk or formula in the cup, or you can try some water. I was worried because my son only wanted to play with his sippy for several months, but at his 9 month check-up, his doctor said that right now, the point was really just to get him familiar with it. Suddenly, around 9 1/2 mo, it was like he got it, and now he drinks from it with no problem.
As for starting solid food, I think that depends more on your son's development than his age. Is he sitting unsupported, crawling with his tummy of the ground, etc. Gerber has a lot of info on their website: http://www.gerber.com/feedingplan . We started with Cheerios and Gerber Puffs, since they dissolve easily. We then moved on to soft foods, such as small pieces of banana, cooked sweet potato, etc. We were told that bites should be about the size of a Cheerio. You can also move up to the 3rd foods, which have some chunks in them. But if I remember correctly, we didn't do a lot of this stuff until closer to 8-9 months.
Hope that helps!