These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
If "Hayabusa Knight's" first attack is negated with "Magic Cylinder", it may still attack one more time.
If "Kuriboh's" effect is activated during "Hayabusa Knight's" first attack, when it attacks again "Kuriboh's" effect is not applied.
Mentions in Other Rulings
Dark Spirit of the Silent: If "Hayabusa Knight"...is selected with "Dark Spirit of the Silent" it only attacks once, but it may then attack twice per its own effect during the same Battle Phase.
Divine Wrath: You cannot chain "Divine Wrath" to Continuous Effects such as: ..."Hayabusa Knight"...
Energy Drain: When "Hayabusa Knight", boosted by "Energy Drain", attacks, and the opponent's hand is reduced during the battle, the ATK of "Hayabusa Knight" for the second attack is not changed because the effect of "Energy Drain" is determined when "Energy Drain" resolves.
Magic Cylinder: Monsters that may attack twice during the Battle Phase, such as "Hayabusa Knight", that have their first attack negated by the effect of "Magic Cylinder" may still make a second attack.
Nutrient Z: If "Hayabusa Knight" attacks you directly twice, the effect of this card will not activate. The Battle Damage must come from a single attack, not a single monster attacking twice.
Skill Drain: If "Skill Drain" is activated after "Hayabusa Knight"'s first attack, "Hayabusa Knight" does not get its second attack.
The Dark Door: A single monster may still attack more than once while this card is on the field, such as "Hayabusa Knight"...
The Unhappy Girl: If..."Hayabusa Knight" attacks "The Unhappy Girl" in attack position, they cannot attack again that turn.