What is the difference between putting skill points in Tumble and getting the Dodge, Mobility and Spring Attack feats? I’ve read the descriptions and they seem to do the same thing. Can someone explain the difference to me?
Thanks.

Five points in Tumble will add one point to your ac, especially while moving around in combat, or if you are rushing up to engage an enemy in combat, it helps you to avoid the attack of oppurtunity they get if they are stationary. While they read the same, they actually work opposite to eachother? in that you get the dodge combo while engaged, and the tumble while moving to engage.

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.

Thanks, I think...still a bit confussed reading that, I'll have to re-read I think.
So it looks like I'll go for Dodge, Mobility and sveral Tumble points. Then if I don't know what to do with a feat, Spring Attack :D

One other question. Is it just initiative that decides who attacks first in combat? Or as I'll have a low dex level I'll never get to attack first no matter what my initiative bonus is?

I see no reason you cannot do both, and it would be beneficial to do so. You can't take Spring Attack without Dodge and Mobility anyway, and there is no such thing as a bad combat feat, except for that monk thing, Circle Kick...