The Past Perfect

[Humble]

Hi, dear teachers,
It’s the toughest of all the tenses for me. Could you please explain its usage in the following excerpts? I hope there’s enough context.

1. They [all four of them] used to get together at weekends playing Fleadh cheoils or music festivals, mainly as a pastime. Thoughts of fame and riches were a world apart.
Brian and Noel had taken tin whistle lessons at the Pipers Club in Thomas Street in Dublin, while Derek took up the mandolin for no better reason than his father played it.

had taken is clear, but why took up and nothad taken up?

2. During the summer of 1963 the four of them had hitch-hiked across Ireland, from Dublin to Kerry.
The moment in the past is marked. Why not the Past Simple?

TIA

[rewboss]

1. Brian and Noel clearly took tin-whistle lessons before they started playing in the music festivals. It's not stated exactly when Derek started playing the mandolin -- it could have been before or during this period. The wider context would make it clear.

2. I think the past simple would be better here, too. If the first word were "By", I would have no problem with the past perfect, but here it seems out of place and unnatural.