Ok great, i wrote you full reply and somehow it haven't post it. I sum up.
For transparency:
<plugin name="textfield"
background="false"
Then changing the data in every scene, check my reply here:
Text field changes acordding to scene
How to make it disappear after few seconds, fastest way i can think of is to creata an action and put it onstart. Like this:
<krpano version="1.0.8.14" onstart="action(disappear);">
<action name="disappear">
wait(5);
tween(plugin[textfield].alpha,0,0.5,easeInQuad);
set(plugin[textfield].visible,false);
</action>
This action will first wait 5 seconds, then tween textfields alpha to 0 and make it invisible. If you just tween alpha="0", the plugin will remain there but transparent.
There are better way to do these for sure but there are at least some reference how it can be done :) Hope it helps!
Regards,