I don't know if PGraphics is fixed yet. In the Beta version of Processing that was how you drew to a virtual applet and then you could paste it about like a PImage. I'll leave that one for someone else to answer. As for textures we have some useful objects in Processing called Quads. You make them with the beginShape() command and they don't even require opengl as such, it just goes like the proverbial off the shovel if you do use opengl.
Code:

PImage picture;
void setup(){
size(400,400,P3D);
picture = loadImage("pic.gif");//a 100x100 .gif
}
void draw(){
background(150);
translate(200,200);
rotateX((PI/400)*mouseY);
rotateY((PI/400)*mouseX);
beginShape(QUADS);
texture(picture);
vertex(-100,-100,0, 0,0);     //top left
vertex(100,-100,0,  100,0);   //top right
vertex(100,100,0,   100,100); //bottom right
vertex(-100,100,0,  0,100);   //bottom left
endShape();
}
 

You can use a function called tint().

http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Programs;action=display;num=1126108058;start=1#1

I imagine it would work but I haven't tried using PGraphics yet. I think they're called PGraphics2 and PGraphics3 now (in respect to the drawing modes). You create them as new objects (virtual = new PGraphics(width,height,null);) and then draw to them as methods of that object (virtual.background(0);).

Found some references to virtual applet space

http://processing.org/discourse/yabb_beta/YaBB.cgi?board=SoftwareBugs;action=display;num=1126623602;start=0#0

http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Programs;action=display;num=1124291770;start=7#7

I suggest you experiment with loadPixels() and updatePixels() in your code too as they seem to fix some shennanigans with images in memory.

I would be a little meek about your aims though and do a search on any bugs you find.