Hi LBH !
There is no need to restart the computer after a sample rate change.
The sample rate changes should be smooth, but I discourage people to manually change the sample rate from the ASIO driver or CoreAudio on Mac.
The application that uses de device will set the correct sample rate depending of their needs.
Let's say you open a project in your DAW, the DAW should be responsible to set the freshly opened project sample rate to the device.
This is why we choose not to put the sample rate control in the MFCC.
Sometimes, depending of the open applications, changing it manually can result in audio glitch or unwanted behaviour.
Now, for the MiniFuse 4, I cannot say the price, but I can say that the device is in production, and the release might be in the upcoming weeks.
Yes, the MiniFuse4 do have an external power supply, but can also work using the USB power only.
Have a good day
EDIT: I have removed Jonesinkclear post, as it was a spam. Bots are clever these days, and comes up with auto constructed messages that seems to give a valid answer, but they add spam link by editing their messages afterwards. Nice one bots, but not to me