Attacking is not the same as activating an ability (compare C.R. 508.1 with C.R. 602.2). Notably, it's not the same as activating an ability with T in its cost, even though, in general, a creature becomes tapped as it attacks (C.R. 508.1f).
Thus, for example, a creature isn't kept from attacking merely because its activated abilities can't be activated.
Yes he can and no it's not. Declaring attackers is a turn based action, it doesn't use the stack, and cannot be responded to. An activated ability is defined by this template:
[cost]:[effect]
Every activated ability has this template, and an ability that doesn't is not an activated ability. Look for the colon, either in the text of the ability, or in the rules for a keyword ability (where it will also be spelled out, that the ability is an activated ability, if it is one.) Examples of keyworded activated abilities are Equip, Forecast, Cycling, etc.
Thus, for example, a creature isn't kept from attacking merely because its activated abilities can't be activated.
[cost]:[effect]
Every activated ability has this template, and an ability that doesn't is not an activated ability. Look for the colon, either in the text of the ability, or in the rules for a keyword ability (where it will also be spelled out, that the ability is an activated ability, if it is one.) Examples of keyworded activated abilities are Equip, Forecast, Cycling, etc.
Former Rules Advisor
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