Parenting/Marraige isn't for cowards!!

Here we are again in the month of September. It is beautiful outside with the leaves beginning to change and the cool breezes blowing. As much as I would love to enjoy this beginning of fall, I am consumed by the duties of keeping up with our Party of 6. We have one turning 21 next week and one turning 18 the week after. As if regular birthdays aren't enough, these are two "biggies". Fortunately when they are this age they pick out what they want for presents. But as they get bigger, so do their presents (expensive). Then there is our youngest who is 5 and just beginning his life in school. I went with him on a class field trip to JH Stepp Apple Orchard yesterday. He still thinks he can do what he wants when he wants and has a hard time listening or joining in with the object lessons or interesting stories the ladies on the orchard wanted to share with the kids. I am having such a hard time with him not cooperating and not wanting to be a part of the group. Also, from the minute I pick him up from school he begins talking and doesn't stop. Then he wants me to comment on what he has said. My goodness, he has this imagination. He isn't talking about what he did today or wants to do tomorrow, he has all of this imaginary story that he tells and wants me to agree that it will all come true and that we will do it. He cries if I don't agree! He cries if I ask him to take a break and play for a while. He cries if I try and get him to walk faster or carry his bookbag. He basically melts down or cries or gets angry about everything. Parenting all of these different ages is a challange. Any advice would be great!!