I know for sure that DiskCopy will work, however that doesn't come with OS X (anymore at least). It's 'replacement' is Disk Utility, but I don't see any floppy specific options in there... it's all "Burn" this or that. Normally (in OS 9 or earlier) you would run DiskCopy to write the image out to disk. Since I don't see a similar option in Disk Utility, it might not do it - but I don't have a floppy drive either, so maybe it will only show up when one is present. Try Disk Utility first, and if that doesn't work, you may want to try using DiskCopy from Classic.
You could also download DiskCopy from Apple and install it on the SE/30, then copy the disk images to the hard drive as well and build the disks on the SE/30. This might be a better way to go since the SE/30 floppy drive is ancient by now, and might not like disks formatted in other drives that much. It will also clue you in to any problems that may exist with the drive as you make the disks (if you get lots of failures, etc.). Make sure you verify the disks after you build them as well, if there is a problem you don't want to be on the last install disk and have it die - leaving you with a nice grey doorstop until you manage to cobble together a working disk. Build all of the disks - some of them you may not need depending on what install options you choose, but you won't know which ones until you are installing things (the installer will skip certain disks if they are not needed). The images by themselves are worthless (for install purposes) until you write them out to floppy, unless they are part of a network install image.
You can download the 'latest' version of DiskCopy from Apple for free. I think you need at least v4.2 to be compatible with most of the images available from Apple. As I was writing this, I realized that you didn't get the images from Apple - you should know that you can get most of the final System versions directly from them. See
this page, and browse a while; lots of goodies. Apple is also kind enought to include instructions in an accompanying text file. Also note that System 7.1 has never been a free download from Apple - it contains some bits that apparently they never wanted to release for free. Assuming however, that since your SE/30 already has a copy on it, somebody bought a license for it at some point - I also don't think that Apple would really care at this point anyway. You can get 7.0 and 7.5 from Apple (argueably, there really isn't anything extra in 7.1 over 7.0 anyway). I recommend sticking with the Apple stuff, as it's a bit easier to work with. The site you reference seems to have a different archive format for every stinking disk. Uggh.