Aren't girlfriends wonderful! ??? My best friend gave me tons of hand me down stuff from her two girls when I was pregnant, clothes, swing, snuggli, jumper, crib mattress, excersaucer ++++++. Some of the clothes had stains, I sat on the floor with a big beach towel, and used the "clorox pen" to meticulously go over each of the stains, then soaked the clothes in biz & water, and then just ran them through the wash with Baby All. They all turned out perfect! I had purchased a couple of "special" things in small sizes (coming home outfit) etc, but mostly - the things from the shower came in larger sizes, and the ones that didn't - I did exactly what you said, and exchanged them for larger sizes. It worked wonderfully for us for about the first year and 1/2! I would also - start buying diapers now, just get a package here and there, and with the ones that you most likely will get at the shower - you might not have to buy any for the first 6-8 months! (the little ones have a zillion in the package) I preferred PAMPERS SWADDLERS when my daughter was tiny tiny. They really seemed like they fit well, and were softer than some of the others, and very absorbant. I tried the Walmart brand and she got a horrible rash immediately. My sister swears by the Toys R Us brand, and buys them in bulk when they go on sale, but I didn't have much success with them.
One thing to not forget - receiving blankets. I had several beautiful fluffy fleece blankets, quilts, etc, and no receiving blankets! It didn't even occur to me until it was time to leave the hospital. Thankfully, it was coolish out, so the fleece blanket was fine in the car seat, but really too much to "swaddle" her in once we got home. We ended up using a large cotton dish towel for the first week or two because I just didn't feel like going out to find some when she was first home.
Also - a little tip. If you are registering for car seats. Go with a "travel system" with infant seat that hooks to stroller. We had the Eddie Bauer one, and the guy at Babies R Us was really helpful in showing me how certain ones have a tendancy to tip or rock forward if another child goes to the front of the stroller and grabs the carrier to step and get a look. Some of those infant seats are only held into the base in the car by a little spring loaded button that pops in and out of a hole in the base. The one that we had, has 2 metal claws that open and close, and fully encircle a metal rod in the base of the seat in the car, AND on the stroller. As an added bonus, it also locked onto shopping carts! (you have to pull the red handle to engage or disengage the claws) After one year - go ahead and go straight to the BRITAX seat with the 5 point harness. You can go to You tube, and search "5 point harness car seat" and you will see a video that will make it very clear why NOT to go to a booster seat, and why you should use the Britax or 1 other brand at this time the name escapes me. Most of the bigger car seats say "20 - 50 or 60 or 80 lbs" (depending on the seat), and then in small print it will say "up to 40 lbs as a 5 pt harness, and then converts to a belt positioning booster to X # of pounds".
Good luck! And have fun enjoying that new little baby! When are you due?