hemlock is a soft wood and will burn quick, birch is a harder wood and i would grab as much as you can, as far as amount used, the first year i found myself packing it full. dont, 3 or 4 logs will burn for 12 hrs in most cases, at least for me it always has, i used 6 to 7 cord last year but that is misleading because if i split everthing it would be alot more. my rule is, if i can lift it and it fits in the stove, let it alone, having said that , after `12" inch round, i usually split it. you can burn rotten wood that has been laying a long time, just do it early in the year. as for telephone poles, the old ones were cresoted and that would smoke so bad a ten mile area around you would hate you forever.