The corners are a subject of great debate.
Most times we will install one wall first and then the next wall. We like a tight silicone joint of 1/8" no greater. 1/4" tile spacing is quite a lot these days - have you seen a tile mock up?
If the client has deeper pockets and really does not like silicone in the corners we can lace the inside corner where we alternated the tiles in the corner so one tile laps over the other. This makes sure there is not one long path up the corner. A laced inside corner is very strong - much like a dovetail joint.