First of all: great shots, well done!
The colours are very good, and the
backgrounds are smooth and not distracting
at all.
1. is a Green weevil of some sort. There's a dozen similar species
which can only kept apart by specialists....
2. a bug from the Heteroptera suborder, google it. There are many
many species and I've never seen this one... They can all be
recognised by the triangular shield behind the head.
3. a fly indeed
but I don't know which one
4. a katydid, yes, a young grasshopper....