6 birds, 4 eggs a day. who not laying?

[lazy gardener]

Rhode Island Reds. Never got 6 eggs.
So I'll check the vent (that wil be a new adventure!) If I find two that the vents are 'tight', then what? Is it possable that they will never lay? Some egss are lighter than the others. Reds have browner eggs?

Most likely means that they will be a bit later to the egg game.

Regarding the 'squat'. I have noticed that when I touch them behind the neck/back , they squat, and 'bottom up' ( like I'm a rooster ?!?!?!?) what does that indicate?

It indicates that they have raging female hormones and are looking for a rooster to "do his duty". If you give her a bit of a feather scratch/ruffle over her lower back, she will then stand up, do a feather fluff/shake, and feel totally satisfied.