[Legolas]

Dodge is a +1 dodge AC bonus applied so long as you're not flatfooted.
Mobility is a +4 dodge AC bonus applied when enemies get an attack of opportunity against you so long as you're not flatfooted. Dodge AC bonusses are cumulative.
Spring Attack makes it so that your enemies don't get attacks of opportunity against you for moving through their control zones.
Tumble makes it so that you get a dc 15 check against enemies getting an attack of opportunity against you for moving through their control zones, and gives you +1 AC for every 5 base skill points.

The Dodge feat is always useful. The Mobility feat becomes less useful when you have Spring Attack or Tumble, but there are other ways of provoking an attack of opportunity too.
Spring Attack works 100% of the time, whilst Tumble can fail (on a roll of 1, for example, depending on server settings). If you have one of these two you won't really need the other, and usually Tumble is the better choice for its AC benefits.