QIf this follower is on my field, and I summon a Dragoncraft follower, since this follower is giving it Ward, can I immediately engage it?

AYes, you can.

QIf an opponent has an engaged follower with both Ward and Intimidate on their field, do I still have to attack that follower?

ANo. Intimidate takes precedence over Ward, so that follower can't be selected as an attack target.

QAn opponent has a Garyu, Supreme Dragonkin that is giving an engaged Jadelong Tactician on their field Ward. If I declare an attack on the Jadelong Tactician with Riko Kashimoto [Planned Perfection] and destroy Garyu, Supreme Dragonkin with her Strike ability, can I change my attack target to the enemy leader since the Jadelong Tactician no longer has Ward?

ANo. You can't change the attack target after declaring an attack.