Is the Orient Star RE-AU0006S00B a good first automatic watch?

Yes, if you want a dressy automatic with an in-house movement and a power reserve display. It is more refined than Orient's entry divers but still approachable for a first serious watch.

Does it have a power reserve indicator?

Yes. A gauge on the dial shows how much running time is left, and the movement reserves about 50 hours when fully wound.

Can you wind it by hand and set the hacking seconds?

Yes. The movement hand-winds and the seconds hand hacks when you pull the crown, so you can set it precisely.

Is it safe to swim with?

No. It has no screw-down crown and only modest water resistance, so keep it away from swimming and showers.

How does it compare with an Orient Kamasu or a Swiss dress watch?

It is dressier and better finished than a Kamasu, with a power reserve the diver lacks. Against Swiss dress watches it gives up brand prestige and bracelet quality but keeps an in-house movement and sapphire crystal.