What do theese feats do?

[Voidstar01]

Right, so i'm playing a Dragon PC and im wondering what these feats do?

Flyby attack and adroit flyby attack, what do they actually do?

and does the repeated effect from clinging breath reapply ride-along effects from my breath?
for example if I use the entangling breath feat, Does the entangling effect get re-applied when clinging breath triggers the following turn?

[Nifft]

Flyby Attack: http://www.d20srd.org/srd/monsterFeats.htm#flybyAttack

[Biffoniacus_Furiou]

Flyby Attack allows you to take a move-action to move, then take a standard-action at any point during that movement without interrupting that move-action. So if your speed is 50 ft., you can move 20 ft., attack or cast a spell or use a breath weapon or activate an item, etc., then move another 30 ft. in the same turn.

Adroit Flyby Attack is the Spring Attack version of that. It does the same thing but only for a standard-action attack, and that movement doesn't provoke an AoO from the creature targeted by that attack. It's basically a different version of Spring Attack for flying creatures that wouldn't want to spend the feats qualifying for Spring Attack.

[The Viscount]

Note that despite the name, you do not need flyby breath to use your breath weapon during your move. It doesn't really do anything except be a tax for Strafing Breath.

Clinging breath mentions that it only works on breath weapons that do damage, and only mentions dealing damage in the following round. You might be able to get away with using Lingering Breath to do this.