Hello yellowstrawberry;
Love your screen name by the way! WEll, I don't know a thing about buzz tools, but think I can help you get your designs to your machine at least. I have a 4000-d also...love it ! I use a memory stick to move the designs to the machine, because my machine is in a different room than my computer and I currently don't have a laptop to dedicate to embroidery. To get them onto your memory stick, plug it into the usb port on your computer, notice what drive it is when it comes up so you can remove it when you are done. I set up folders on my memory stick so the designs are easily located, from there you simply go to the folder on your computer where your designs are located then drag and drop them onto your memory sticks appropriate folders. then remove from your computer, by going to your safely remove hardware icon click when it comesup click ok , remove stick. Now you are set to take to your machine and plug into its usb port. turn the machine on when it it comes up go the the one that looks like 3 lines on it, touch it and the designs on the memory stck will come up by folders names, touch one of the folders and it will come up on the machine. When you do this the first time it may take a few minutes to appear on the sreen so be patient.
Ok....does t his make any sense to you at all??? I hope so, I can do it better than I can tell how to,lol I am sure there are many out there who have used buzz tools and will be able to help you with that too.
You will love your 4000 once you get to know all the in's and out's. Did you know that there are some applique things on the machine already? This is a total kick butt machine!!
I would also suggest checking with your local Brother store near you to see if they offer a class on this machine, many do. It will show you where all the stuff on your machine is and whatit is capable of doing. I think the class may run about $35-40 but it is so worth it. They will also usually answer many of your questions for you.
Another thing that I always reccommend is to sit down, take some time and go through your manuals you go with the mchine. I take it a chapter at a time, go through, locate what they are discussing then actually perform the function. It really helps you to go through it hands on. I know you want to start using your machine right away but it really is worth the time to do this.
Hope this helps you out a little bit at least. I know there are many out there that have used buzz tools nad can help you with that, I have PE-deisign 8 so cannot help you with Buzz tools ....sorry
Let me know how you come out 
Judy 
Help me to start each day with a new attitude and plenty of gratitude!