I got told all of those things too and it really scared me. Gosh some people just like to point out the negatives but the positives outweigh them by a mile.

DD adored her brother from the first time she met him. My biggest problem was making sure he didn't get smothered to death by her hugs and kisses. She didn't go back to nappies or stop sleeping and in fact I think it made her grow up a little bit as she wanted to be the 'big girl' and not 'the baby' anymore. It really is awesome! And even if your DD is a little jealous then that is completely normal and understandable and won't last long, I bet they will be the best of friends