Increases to attributes aren't increases to Initiative; that means direct increases to Initiative, like the bonus dice from augementations and spells. Improved Physical Attribute (Reaction) is the only way to get +4 to REA as an Adept without looking for another source.
Increasing your MAG does indeed give you a Power Point. The metamagic is there to get PP for much cheaper (7 MAG is 35 Karma, your first initiation is 13) or if you want to just *seriously* load up on points, or if you're so far advanced that there's no other metamagics you want. Keep in mind that regardless of where the PP comes from, the maximum level you can have in any Adept power is equal to your MAG attribute (or the power's own limit, whichever is lower). So if someone initiates a lot but doesn't increase their MAG, they could end up hitting the cap on some things, especially when combined with Qi Foci.