1. Yes, GrowthBook itself doesn’t really care where you’re running the SDK.
2. Yes, though if you use mixpanel, its easier.
3. Yes, they can be similar, and can be the same in many cases - but how they are used are different. The attributes are used for targeting, and the dimensions and segments are used only for analysis (and don’t effect exposure). Targeting attributes are simpler to use as they require no SQL, but you do have to define in the SDK the values of the attributes.