New project questions

Hello there,

New project but i have to R&D to find if i can do it.
The customer makes box-shaped furnitures, like ikea ones (see picture)

Those are coming in several flavours : 1×2, 2×1, 2×2, 2×3 and 3×2 (squares)

Let the end user change colors and number of doors (small squares ones, or double sized or even triple-sized ones, options…) i can do.

BUT

After choosing colors and doors and options, the new setted furniture has to be manipulated beside (or above) other ones, so the end user can create a full wall of square furnitures.

So questions :
1 – How do i let the user to move an object to be “snapped” beside an already placed furniture ? (beside or above if less than 3 meters for ex.)
2 – How do i let the user to select onr specific placed furniture to let him change colors, doors, options ?

Any help for knowing where to start would be nice… will i need Dictionaries or some dev-oriented stuff ?

Regards.