Containers are designed to be wind/water tight and are inherently very secure.

How to remove the mold, should I use Drywall mold tough and how to watertight the house from outside.There were wood panels which caused to grow the mold. 

Is the basement watertight and free of mold/mildew?

Also, your basement contractor is correct about breathing - a basement is not a submarine, it's not supposed to be watertight.

Because of shared wall and roof etc.....even potentially electric depending on how lines are run etc....can I make repairs as needed to both sides....common wall framing, roofing etc that need to be done to keep my units water tight and structurally sound and then put mechanics lien on that unit?  

If done properly it will be water tight.

Tenants want utility/mud room on concrete floor water tight.

Any leads on where I can get a boiler plate semi water-tight application like that to further refine?

I selected it based on the thick wear layer, water-tight field, the relative flexibility (to go over an imperfect floor), the floating system and not the least, the color option (lol).

Here are a list of things you should probably be checking quarterly to maintain a good safe unit that also appreciates.​Interior:​Exterior:​Holes in walls, ceilings or floorsInsect/rodent infestation (including bed bugs)Weather/water tight (weather stripping)Hot water (minimum temperature of 110˚F)Peep hole/keyless deadbolt lockMissing electrical switches or cover platesExposed wiringInoperable A/CInoperable Heating Water tight sink, water closed, tub or shower (missing tile, etc.)Water LeaksSmoke AlarmsImproper sewage discharge​High weedsLitter GraffitiJunk Motor VehiclesPot holes in parking lotBroken windows/doorsDecayed/exposed woodUnsound stairs, rails or balconiesTrip hazards Holes or cracks in wallsInadequate security lighting