Hello Kevin,
Wittingsthal is still in business today! The foundry exists since 1651 in Johanngeorgenstadt (Saxony). Since the market for stoves declined they changed their product range to domestic engeneering. Nowadays they produce soild fuel bath boilers for eastern Europe and all sorts of plumber´s equipment like valves ect.
I suppose the firebrick under the cooktop is meant to protect that area... Lignite briquettes are - and were always - the cheapest fossil fuel for domestic use followed by coke and high volatile bituminous coal. Reckon the people who built the stove knew the characteristics of the fuels on the market and assumed that a houshold that opted for a mid-range stove is on a budget and won´t spend money on expensive coal like anthracite. There´s nothing wrong with Lignite Briquett and the high volatile bituminous you can buy here, but both contain up to 40% (!) volatiles; there´s no problem if you work in layers and give the volatiles time to cook off. But you´ll get a roaring fire with very long flames for more than 1 hour if you dump a full load in a hot stove!
