With social media purchases, make sure you always ask for references when working with someone new, and trust your gut (if a deal seems too good to be true, it probably is), and you should be fine
These two modes have their place and are good in different situations, but this is still super clunky
White and/or blue are musts for color identity, with access to both colors being preferred, and the lower the mana cost of your commander, the better, as it will be easier to cast
There will always be one player at the table who most threatens your life total, and most lifegain decks also want to keep life high for the likes of Aetherflux Reservoir or game-winning triggers
It just produces one mana of the appropriate type, with no restrictions or riders
What affects the value of Despark