well on the amiga itsself you just need to use a tool similar to https://ftp.uni-erlangen.de/aminet/disk/misc/ADFer.lha
which can read/write adf images, or if its games your wanting to rip, try and find a suitable whdload installer at http://whdload.de/download.html
making images of the disks is easy enough on the amiga side, transferring them is the pain in the arse part, if you have an amiga with a cd/dvd writer then thats simple enough, both pc and amiga can read/write them no problem.
The standard problem with other storage devices is the differing filesystems, there are ways round it for both systems but they tend to be a pain in the backside to setup and typically arent as easy as plug n play, a cd writer imho is the better way to go, you can just burn all your created adf/whdload files onto a cd then do as you want on the pc side.
another handy gadget for the amiga side is http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=1269
its pretty handy, replaces your floppy drive and lets you plug in usb sticks loaded with adf images, i assume if 1 of your amiga's has already saved a ton of adf images to HD, then you could plug in that badboy and write those adf images to a blank adf image on the usb stick, or maybe theres a simple copy over method, i dunno, not tried one yet.
Heres an old writeup on it, https://cortexamigafloppydrive.wordpress.com/