ok...

1. do yourself a favor and do a steady shot. no handheld, nothing. put the cam on a tripod thats the easiest way to do it.. and dont touch it.
then you need some infos.
you have to get the sensor of your cam, the lens and take some measurements. e.g. from cam to actor. from cam to ground and the angle of the cam. when taking those measurements its best to set the start where approximetly the sensor sits. dont measure from lens to actor.

you then in maya create a cam and import the footage. with the measurements you have taken its now simple to set everything up. when it should go around the arms then model it and place it. what is easy since you got the approximite distance from the cam. then do the particles in whatever fashion you like. use the geometry as a mask. hw particles have the option mask geometry and in sw particles set the matte option for the object to black hole.

put this in a compositor to tweak the final result and thats it... or directly in the editor. dont know how much you do/dont do.

so thats it. sounds easy, but it is a hell lot of work good luck.

2. dont know what you mean but you can do that all in maya.

greets