Henry Wadsworth Longfellow wrote the words to this song (originally a poem) during the Civil War; might explain verse #3.
Be careful with the Accidentals.
Mid Measure Repeat: Sometimes a phrase of music or a verse of music does not fit neatly into the measures. To keep the verses straight the repeat sometimes goes in the middle of the measure. Here the return repeat goes before count 4 of measure 2 and the repeat is after count 3 measure 10. You just have to put those two measures together to make a full measure with all 4 counts.