Rendering primitives

Really an OpenGL question, but I am using LWJGL so I thought I would psot here.

I have the following code that draws 200 primitives (GL_LINES) to form a “criss-cross grid” taht is 100 by 100 in size.

I have a few questions on this…

            float xx = -50f;
            GL11.glDisable(GL11.GL_TEXTURE_2D);    
            GL11.glColor3f(0.0f, 0.6f, 0.0f);
            
            while(xx < 50) {
                  GL11.glBegin(GL11.GL_LINES);
                        GL11.glVertex3f(xx,0f,-50f);
                        GL11.glVertex3f(xx,0f,50f);
                        
                        GL11.glVertex3f(-50f,0f,xx);
                        GL11.glVertex3f(50f,0f,xx);                        
                  GL11.glEnd();
                  xx += 1.0f;
            }
            
            GL11.glEnable(GL11.GL_TEXTURE_2D);
            GL11.glColor3f(1.0f, 1.0f, 1.0f);

1 - It seems to run well with only a single avatar (cube), would a triangle_strip be a better choice? May evenutally have 16 avatars or 32 avatars and numerous projectiles.
2 - The avatar (cube) sits so that the lines run right thru its middle. As long as you are on the grid, there is at least one line always running thru you. Would collision detection with this be a simple as looping thru the lines and checking for intersection with the cube? I want to make sure your cube is on the grid so you dont fall off.
3 - Simple, tiny projectile. just a smaller cube?