Evolving questions

You can evolve whenever you want, the CP bar only means the level of the pokemon, it doesnt matter if you evolve at lvl1 or at lvl40, nothing will change.

In Go, you can evolve Pokemon at any time, as long as you have enough candy for that evolution line.

Whether you evolve-then-power-up or power-up-then-evolve, the outcome is functionally the same. Generally speaking, it is better to evolve first to see what moves you roll before deciding if you want to power up and possibly use TMs to try to fix the moves.