Is this jacket fully waterproof?

Yes. It is described as waterproof, with an attached hood and adjustable details to seal out rain. Seams and coating specifics are not stated, so treat it as a rain shell rather than a drysuit.

What weather is a midweight rain jacket for?

Spring and fall rain, cool wet mornings and steady drizzle. It is heavier than a packable emergency shell, so it handles longer time outdoors but can feel warm in hot, humid rain.

Does it have insulation?

No. It is a shell, so you layer a fleece or sweater underneath when temperatures drop.

How should I choose my size?

Pick your usual size for a close fit over a shirt, or size up if you plan to wear a sweater or hoodie underneath. The adjustable details let you tighten the fit.

Can I wear it for hiking?

Yes. The hood and adjustable fit suit trail use in wet weather. It is not the lightest option for long backcountry trips, where a packable shell is easier to carry.