I recently got access to summon a couatl and I have a few questions.

It's immune to any effect to detect it's location. If it becomes invisible, would see invis/truesight work on it since the only reason you can see it is because of the spell effect letting you detect it's location?

I know I can't shape shift into things with "classes" but I can use natural magic. If I shape shift into say an oracle, use some of it's 1/day spells and reactions, shape shift back into a couatle or another creature, then back into an oracle, can I use the 1/day spells again since it's technically a "new" oracle?

What are some good things to shape change into? So far the oracle is strong with it's 3x a day advantage on any rolls. Sahuagin warlock of ukotoa, and the weretiger.