My most important question: Which is better, staking or investing?
Staking doesn't produce anything of value, it's just useless inflation. For every "free" coin you get by staking your portfolio is depreciating by a similar amount (or more, if some other bagholders have masternodes or some other contraption that produces more inflation).
Staking does not produce any value, investing is not that of a stable.
You better use both to minimize possible losses I guess