The effects of multiple such effects are cumulative
Personally, if I want a specific card, i'll just grab it instead of buying and ripping boosters to get it
In a Commander pod, Lord Xander has a little more room to operate, because theres a better chance that someone will discard multiple cards, plus you get to play kingmaker on their permanents once Lord Xander dies
At zero cost to yourself, you tap it and gain G per creature you control
Its one of the rare cases where a card uses an X, but not in the casting cost
Back to Basics (Hoser) Perhaps the best non-basic land hoser in all of Magic , depending if you consider Wasteland a hoser or just a good land destruction effect