Moving Objects and/or Particles first controlled, then randomly?

Hi,

I am looking for a 2 ways to animate a lot of layers/texts...

I would like to know about: first using expressions, second using TC Particular.

First:

I am using this expression:

tMin = .25; //minimum segment duration

tMax = 1.0; //maximum segment duration

minVal = [0.1*thisComp.width, 0.1*thisComp.height];

maxVal = [0.9*thisComp.width, 0.9*thisComp.height];

end = 0;

j = 0;

while (time >= end){

  j ++;

  seedRandom(j,true);

  start = end;

  end += random(tMin,tMax);

}

endVal =  random(minVal,maxVal);

seedRandom(j-1,true);

dummy = random(); //this is a throw-away value

startVal =  random(minVal,maxVal);

ease(time,start,end,startVal,endVal)

It moves around the object/text randomly from one to next position. How can I define the starting position. I would like to have control of the movement first (by using keyframes or moving along a path) and at a certain time make the object move randomly / drifting.

Second: I would like to achive the same with Particular.

The first part of the movement of the particles (not the emitter) should be straight upwards. After a while (let's say half the screensize), the particles should start to move randomly in space / drift.

I don't understand how to do it. I have a Point-Emitter.  Using direction "Directional" makes them drift out of the Composition. Moving along a path makes them stop at the end of the path and "Air Resistance" can't be changed with keyframes. I am not very firm with Particular I must admit...

Thanks!