For the first three items, why not use standard sms/multi media format. 140 characters and pictures or video verses 90. It also reaches most (effectively all?) cell phones.
Well a normal message requires the sender to have the contact details of the user or something the user have to actively do (download a app, send contact information over, etc.)
The cellphone alert is standardized thing on newer phones. In my country it's turned on by default, when you get a phone.
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