"ADVICE" AnyOne With Multiple Young Kids

Okay, so I have a now 3year old boy who will be 4years old in May. A now 8month old boy who will be 1years old in May. And I am now 25weeks along with baby girl who will be born in May! I am terrified! We have both wanted a little girl for so long but, we were hoping the kids would be spaced at least 2years apart, but hey things happen and were still really excited either way! I just need some advice on how to handle this tho! My almost 4year old is ADHD/ADD and my 1year old is spoiled to the core and alone they are handfuls so this is definitely going to be a hell of a roller coaster! Any advice what so ever would be soooooooo EXTREMELY helpful!

My 2 little turds! "OH YEAH!" And did I also mention I have a therapy pet Chihuahua? Well, I do! And he is also spoiled ROTTEN! I think he thinks he is one of the babies. lol