I just did this in one of our rental bathrooms where wallpaper had been painted over a bright pink by a former tenant.Buy some inexpensive liquid fabric softener at the dollar store...along with a spray bottle.   

I'm not 100% sure but they may only sell the slabs (very cheap) and refer you to a fabricator to make the actual countertops, pretty much like Bedrosian.

At this point, I would be more concerned on the condition and performance of the infrastructure:  fabric/envelope (insulation and air sealing, windows & doors, roofs); HVAC; DHW; electrical, etc. as those will be the most disruptive and expensive items to address. 

(There are plenty of others, but these are among those that make up our rich cultural fabric).

So colorful pillows, sticker cut-out designs on the old wood, colorful fabrics & cushions, inexpensive but better looking lighting, fake flowers, bright multi-color paint for the outside of the trailer, and hula skirt for the trailer..

Shower wall is the full sheet (vs tiles, marble/natural stone which requires custom fabrication). 

Think about any fabric left in the house- drapery, even a simple towel, can make the house smell so make sure that you are looking for those items too.  

I got out of the military in July 2016 and I'am currently working with my uncle at Steel Plate Fabricators in Knoxville, TN as a assistant welder.

Should a fabricator be telling you when they are planning to add seems?

You then just have to install them, rather than fabricate them first then install.