Newbie Kwestion

I'm finally building my 10' long 7' tall book cases!:)

My plans are to:

• do all the cuts
• build the face frame
• sand everything
• dry fit
• use blue masking tape to tape off glue areas
• stain
• use 3 coats of deft laquer

Do I sand in between each coat?
Is this the best approach, or should I assemble first then finish?

Thanks

Will a single unit be ten feet by seven feet?

Nope,

I'm going to build 4 units then build a face frame to fake it into looking like one unit.