STD leave

I am considering taking short term disability for mental health made worse by a autoimmune condition causing my body to not process stress well. (FTE, corporate employee)

Taking leave would be a huge financial burden so I need to understand everything fully.

Is it 3 months or 6 months for short term disability? 60% pay right? Can I layer in PTO so there is no waiting period without pay? Should I tell my manager I first want to try taking a week off immediately and then reevaluate?

I hate that I am having to consider this but my health is truly scaring me 😞