Not only will they change consitency but they can produce some beautiful colors!!! I always increased their fluid intake when they started solids since so much of their fluid comes from formula when they are little. The more solids they eat, the less formula they drink, the less fluid they get, the harder their stools.
All of mine drank from a sippy cup at about 8 months but didn't go to them full time until they were about a year. We stopped bottles when we stopped formula. HTH