Will the questions never stop!

I know children ask a ton of questions, but being home all the time takes the question asking to a whole new level!  I thought I had to answer a lot of questions at work.  I used to answer questions and make hundreds of decisions everyday, now I answer and make thousands of decisions.  Obviously I have not quantified the exact number of questions I answer, but it certainly feels like a lot more than when I was working.  The  biggest difference is the type of questions I answer now.  Of course the most common question is, "Why?".  I don't mind answering why questions.  I feel like the children learn when I take the time to answer a question like, "Why do you put the bread in the fridge?" or "Why can't I jump off the deck into the pool?". 

The most stressful questions come in this form:
My youngest will point at something like a mail box and say, "What is that called?"
I respond with, "it's a mailbox".
Which is immediately followed by "Why?".
Then, being the quick mom I am, I respond with "It's a box that the mailman puts the mail in.  Thus it's a mailbox".
Which is immediately followed by "Why?".
The only way I can think to respond is, "Because that's what it's called."

I understand that that sequence of questions and answers is not really stressful, but as I have already admitted, I have no patience.  When I have 10 to 20 conversations like the one above in a few hours, I start to get frustrated.  It's worse when I know the kids already know the answer to the questions and just want to talk.  I have a new appreciation for the saying, "Silence is golden".
When my daughter gets home from school it gets worse, because the questions switch from being innocent curiosity to questioning every rule and value we have as a family.  And as she gets older we get caught off guard with new decisions to make.  Just the other day she asked if she could call her friend at home.  Now that's not really a big deal, but she's only 6.  Does she really need to spend her time talking to a friend on the phone?  Again, this is not an Earth-shattering decision, but it's another one that I need to make.  I get nervous about making decisions at the end of the day because I don't know that I have my best decision-making hat on and I don't want to make a rash decision just because I'm tired of making decisions. 

Maybe, like all things, decision making will just take practice.  And since I am a new SAHM, I need a lot more practice!