Yes, you can look at an outage map, when you are in the middle of an outage (sometimes).
No, you will not get notified of a planned or unplanned outage with the app (or website). There is no way a user can set up notifications for such events. In theory, customer service can set you up for notifications, upon request. You can text "HELP" to XfinityAlerts (87808) and you'll get a limited menu. You can also text "OUTAGE" and you will get status if this outage is planned or documented.
No, you will not get credit for a planned or unplanned outage, under most circumstances, even if you try from this link. You will have to call.
Yes, you can call and ask for a credit, which may (or may not) be posted to your account in 72 hours.