Simple Q&A D&D 3.5 (by RAW) XXIII

[OMG PONIES]

A 288 Yes.

Once per round when your mount is hit in combat, you may attempt a Ride check (as a reaction) to negate the hit.

hit: Make a successful attack roll.

Absent any specification about ranged vs. melee or touch vs. normal AC, Mounted Combat can be used once per round against anything that requires an attack roll.

A 289 No. Paimon's Dance of Death only allows attacks, not activating magic items.

When you use this ability, you can move up to your speed and make a single attack against any creature you move past...

The most common type of standard action is an attack--a single melee or ranged attack. Other common standard actions including [sic] casting a spell, concentrating to maintain an active spell, activating a magic item, and using a special ability.

A 290 No. Dance of Death requires a standard action and is thus incompatible with charging (which requires a full-round action). Additionally, charging specifically allows only one attack.

Using a supernatural ability is a standard action unless otherwise noted.

Charging is a special full-round action that allows you to move up to twice your speed and attack during the action. However, it carries tight restrictions on how you can move...After moving, you may make a single melee attack...Even if you have extra attacks...you only get to make one attack during a charge.