I had not looked into bitcoin mining until very recently, and what attracted me to give it a try was not the prospect of earning meaningful money but that it was a neat project to fiddle with. I have always enjoyed projects like satellite access cards, 3D printers, etc. things with blinking lights and lines of code scrolling by doing cool things. I have no expectation of doing anything more than breaking even but I would like to be a little more focused and efficient.

I already had several raspberry pi's sitting on the bench (original and B+) and plenty of USB hubs and such laying around so no investment there.

First I picked up two 333mh/s USB block erupter and got the pi configured and running the rig. I bought those because they were what was covered in the tutorials I saw first.

I then picked up an Antminer U2 because the GH/s per dollar made more sense than buying more of the 333mh/s USBs.

Then I picked up an Antminer U3 because that had an even higher GH/s per dollar than the U2 so it made more sense to buy the U3.

The next step up from the U3 seems to be the more serious hardware with more heat, noise, etc. and probably more committed than I care to get, but I could be wrong. My questions are:

-Can I mix miner types, can I install the 333mh/s and the U2 on a USB hub and hook in the U3 and have them all recognize and co-exist (assuming proper power of course)

-How many U3's can a pi B+ support, can you have 4 running from one pi with bfgminer?

-I was considering 4 of the U3's with a Pi B+ and sticking with that, is there another miner hardware unit that would make more sense than 4 of the U3s, there are so many of these things it seems like every time I find one and settle on it something with a much higher hash rate turns up for just a few $ more. It is very easy to just keep poking yourself up the chain.

-I saw a few different GUIs for bfgminer that claim to make it easier to visualize and manage the device performance, is there any merit to these, any one better than the others?