Hi there,
YES…? Have you tried it? (seamless experience same as the WiKi web viewer)
Hmmm, Which specifically, The Grove Expansion Boards second item on the list there, both Board and Schematic both are usable in Easy-Eda and generate accurate Gerber files and a solder stencil for SMD components Along with the BOM, further I can have them made with a few clicks from LSC supply and JLPCB, (note, Seed Fusion also can do this) No issue there, if a monkey can do it , You can too! 
What proprietary software. Do you mean Industry standard?
GL 
PJ
btw, on the Live stream the Owner is committed to open source for what they own the IP for.
That’s a pretty bold move IMO. Trend setting! 
