~snip
Is ok you can ignore those, they are looking for arch osx which is not your case.
a) On linux, after we tweak the param.js file and launch an instance, can we change the settings and launch another pair with different settings?
yes of course. I use screen to run multiple instances. Others are familiar with pm2
b) currencies.js : Do we run it separately, before starting supergun, or does supergun initiate the market analysis by itself?
you can run it separately yes: it will update it hourly. Consider it shows you highest volume/highest variance coins. It is up to you to trade them or not.
c) can we have an different strategies running on different pairs? (eg having 1000trades running for BTC_XRP and supergun for BTC_DASH)
Yes. Not suggested to do it on the same pair with the same account.