Hey, calamari, welcome to MobileRead!
Yes, you can just load files via SD/MMC/MemoryStick and read them w/o the Connect software. The down side is that there is overhead while the relatively slow processer in the Reader formats the files for you, and it may not hold your place(s)/bookmarks when you pull the card and reinsert it (not sure about that).
I didn't try any Gutenberg texts while we were out there, but the Librie' formatted Manybooks texts I had with me worked beautifully.
The Brick is not hard-wired, as I recall, but I didn't notice the shape of the actual connection.
The power connection on the Reader side is not the m-USB, it has its own, separate ring & post connector.