Congratulations on your upcoming arrival! I'm sure that you will find that you will get lots of breastfeeding support here!
Having some things on hand before the baby arrives is good, but I wouldn't purchase too much because you'll find that you might not end up using all of the things you thought you needed.
I didn't realize that any wipes were made to specifically clean the breast. I have never used anything like that. I agree with the other post that you should let your breasts breathe both before and after nursing. Get one of the lanolins - they are all pretty much the same - it will help with soreness. You should definitely get at least a large box of disposable nursing pads - you will leak a lot at the beginning. I really liked the Lansinoh pads because they are really thin and absorb a lot of milk. However, I found that the washable Gerber pads were better as my milk production stabilized (around 6 weeks) and let my breasts breathe better.
I have one pack of the Medela parts cleaning wipwa - they are good for occasional on the go use, but the breast valve parts are very small, so it's better to get in there with a small nipple brush - I had to improvise because for some reason, Medela doesn't make brushes for their parts. I would not count on using the wipes on a regular basis. Get a box of the sterilizing bags - they help a lot. While I don't sterilize every time I use the bottles/pump parts, I do it occasionally. I pumped a lot at the beginning because we had some latching issues (which resolved itself around month 7), and I sterilized the parts/bottles every day or two. The best thing to use is soap and hot water. It's the cheapest too!
The Medela bags are good because they fit directly over the pump, but they are expensive, so if you're going to be pumping frequently, I recommend the Gerber bags. They are great. Out of 4 boxes that I used (that's about 200 bags!) - I only had leakage with about 4 bags. They were cheap and if you end up using the Playtex nurser, the bags fit directly into the bottle - you wouldn't have to switch.
I would not use a bottle warmer - I don't feel comfortable with any kind of heating element near plastic intended for baby use (actually, I don't like it near plastic for adult use either!). I warmed all my bottles in a mug with hot water. If you know ahead of time that you need to defrost milk, leave it in the fridge overnight and it will be slushy the next day. If you need to defrost quicker than that, place the bottle/bag in the mug of cold water and then into a mug with hot water. Don't try to heat frozen milk too quickly - it separates. You don't really need the expense of a bottle warmer. Hot water in a bowl or mug really does the job quite well.
As for the bottles, you can try to use the Playtex, but your babe might not care for it. After trying a bunch of bottles, it turned out that my daughter didn't really care how she was getting her milk. She moved from breast to any kind of bottle with ease. I spend a lot of money trying different ones, because I was worried about nipple confusion - I'm not even sure that I believe that there is such a thing anymore! Maybe it's nipple preference....Anyway, I ended up using the Medela bottles, which are one of the cheapest on the market. I did have some issues with leakage when using the Medela nipples with their bottles, so I got the Dr. Brown's nipples instead. They work beautifully.
After talking to other moms who exclusively BF and those who tried and gave up, I have found that the only difference is that the ones who stayed with it knew that things would get easier and accepted that it would be hard for a while. I can't tell you the number of times that I cried - especially during that post partum blues time (mine lasted a little over three weeks) - having a supportive husband is a wonderful thing at that time. It helped me to keep the samples of formula that we got from the hospital nearby, just so I knew that my baby wouldn't starve. It relaxed me enough to help my milk let down. I'm happy to say that I gave those samples away, and she will be 8 months, and I'm still BF exclusively.
As I mentioned before, you will get lots of support here. I've found that it's unlike other online communities - there isn't too much judgment here. Come back and ask questions after your baby is born if you need help! We've all been there.
Everyone says it, but you don't realize it until you're past it that newborn time goes way too fast. It's hard when you're exhausted and feel like you are just the milk lady, but try to slow down for a few minutes each day and cherish it. Good luck to you!