If there were any lands that were also artifacts before the abilitys effect applied to them, those lands would become artifact land creatures, not just "creatures," or land creatures. The effect allows them to retain both the card type artifact" and the card type land. In addition, each land affected by the ability retains any land types and supertypes it had before the ability took effect
Nothing with Blue qualifies
To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there
There are so many ways to break Shorikai and get an 8/8 into play, and while it likely isn't the best Vehicle commander now the rest are able to join the party, it can still hold its own admirably
A battle's subtype provides rules for how it can be attacked
Looking for a mountain of additional information regarding value considerations when it comes to Magic: The Gathering