Um, no. Well, sorta, in that it can use LLVMpipe to JIT the software rendering. Generally, on Linux, the hardware does the hardware acceleration (using the proprietary blobs or the free driver equivalents).

Um, yes. Well, sorta. Most of the open source hardware 3D drivers use Mesa as a front end - a bit like Microsoft writing D3D and the hardware manufacturers only needing to write a relatively small hardware specific bit rather than a full 3Dstack like they do with OpenGL.