Well if your anything like me i had no idea what to get when I had my first or what to expect. There is no need to go extremely overboard buying things unless you have the money and just feel like it. I would say the basics that you will need in the first couple of months is a large quantity of diapers and tons of butt wipes. Only get about three or four packs of the newborn they grow out of them pretty fast but I would have at least ten packs total of diapers before the baby comes home believe me you don't want to have to go out of the house before your ready. A baby bath that fits in you sink and some soft towels and wash clothes and some baby shampoo, soap and lotion are a must have. A manicure set with a thermometer is good to have I always preferred the little scissors to the clippers and a bottle of baby Tylenol. About ten onesies will be needed and about three or four pairs of p.j.'s. A couple of outfits and a couple of security blankets. I had a combo pack when it came to the stroller and car seat it was really nice to be able to just snap the baby in the car seat then be able to transfer them from the car to the stroller really easily. Walmart has a good selection and and they aren't too expensive. If you are breast feeding you will want to stack up on breast pads, the ones with the sticky on the back to help keep them in your bra. At least two nursing bras because you tend to leak into the first one more often then you'd like. One of my biggest things with breast feeding was lansinoh, lanolin. It's a purple tube of cream that you put on your nipples and it really helps keep your nipples from cracking. If your not breastfeeding or even if you are you need to have a couple of cans of formula in the house and a couple of bottles. I always got the easy flow bottles that take the bags. These make it to where you can push the air out of the formula and the baby doesn't get as gassy. For the first couple of months I found it really nice to have a bassinet so it was right next to my bed. With my second child she loved her swing which we got from a yard sale. women are constantly trying get rid of their baby stuff so looking in the paper and yard sales are a cheap way of getting some of the stuff you need.
As for your marriage if you have strong one already a baby should only make it stronger but it will definitely be a challenge for both of you. You might want to start taking now about your feelings on how the baby should be raised so that that won't become to much of an issue later you will already have discussed and come together on how you think things should be handled. Of course there is no way you could possible know everything about how your going to handle things so just be prepared for those long tired nights and some fights. I love to see the father that my husband is and I 'm sure you will too. I hope that this had helped and if you have anymore questions just let me know.
Beth