First off, I'd definitely recommend reading http://gamasutra.com/blogs/JesseSchell/20150626/247113/Making_Great_VR_Six_Lessons_Learned_From_I_Expect_You_To_Die.

First off, I'd definitely recommend reading http://gamasutra.com/blogs/JesseSchell/20150626/247113/Making_Great_VR_Six_Lessons_Learned_From_I_Expect_You_To_Die.php http://gamasutra.com/blogs/JesseSchell/20150626/247113/Makin.... VR-wise, b) can definitely be mitigated. There seem to be two current strategies - either you design the experience to be primarily stationary, or you set up a room that people can actually, physically walk in. stationary-only experiences might seem like a tight constraint, but constraints breed creativity :). Rooms to walk around in have also been done, but they're obviously more effort to set up and maintain, and are typically done by larger institutions.