H.M.
I have three just now. My infant is 3 months old. Plus I have my "older" children which are still young.
I didn't realize how interesting it would be. I fear the older ones are getting neglected right now because the baby is so demanding. I've pulled them in by making mommy help with him. I make them sit with mommy and daddy and help make him happy.
But you can take a baby on an airplane. Actually with the baby it is easy. You can actually hold them on your lap, the baby that is. No cost of a seat! The others you just bring their carseat along with you. So no problem there. I brought a 2 month old on a flight and a 2 year old once. It was fine.
I fit all my my children in one car with 2 booster seats and one of the large convertible carseat. It's in a little compact car and it still works. Most people buy an SUV or a Mini-van though. But I find in most cars you can make it work. It's just a little tight. But they are little people so they don't care, or at least mine don't.
And with the day care you really have to look at whether it is worth your time or not. An infant in daycare can be VERY expensive we found out. I'm staying home because there is no sense in me working and having the children in daycare. We did the math and I'd be making about 2 dollars an hour really. So call around or ask your current daycare provider how much it is for a 6 week old and then see if your cleared hourly wage makes it worth it or not. I wanted children more than anything so that was more important to me. So me and my hubby sat down and figured out if we could do it without my income and only on his. We figured out what we could cut out and decided it was doable. So we did it.
Good luck with your decision! And if you decide on the baby good luck with the pregnancy as well.