Advice on Inca Nut Harvesting

Plants
#1

A partner in Laos is growing Inca Nuts in Phonsavan province. They have sent these questions. Can anyone help?

Question 1: My reading suggests that Inca leaves are edible when cooked.
a. What percentage of leaves can you pick off the plant without harming the plant?
b. Can the leaves be picked at any time?

Question 2: I have also heard of people using nut shells for tea.
a. There are three layers of shells to the kernel. Do you use all three layers for making tea?
b. Do you dry roast the shells before making the tea?

#2

See:

#3

A quick search turns up several mentions of using dried leaves for tea but none about using the nut shells.

#4