If you already have 1 you may as well buy a second one.
Two is much better. Just try it for a week or two and see if it really bricks too much to your taste.
1 is fine, 2 helps if One gets banished. Unlike desperado triamid is easily searched and recoverable from gy. Plus you don't want multiple out since you need other triamid for their effects
Well it depends, right now the only meta deck that i think wont bother this being on the feild with two counters is DM deck, if the opponent cant get rid of it and you can atleast put 1 counter on this during their turn they can only activate 1 monters effect on that turn. If you can put two (2 triamid monters except boss + 1 feild spell) you can lock them from using monsters effect.