Horizontal metal drain pipes are plugged and don't drain,leak at worst times.

In my experience horizontal cracks are most often called out as being a bigger concern structurally than vertical cracks.  

It is horizontal, so the contents will spill out onto the basement floor.2.  

We install geothermal loops and install underground utilities (mainly via horizontal boring equipment).  

The electrical outlet that was moved to the left of the sink was installed horizontally, where as the other outlet to the right was vertical, as was another outlet they moved farther along the countertops.

Depending on how bad is the foundation state (how many inches you have to correct), is very possible the sewer line will disconnect/break in the horizontal portions.

However, in the basement, there is a few horizontal cracks in the wall.

Horizontal cracks in the foundation is a problem that can absolutely blow this deal.

when running supply through attic, 2017 Florida Building Code - Residential requires only hot to be insulated, but make sure you insulate the cold also (attic is 140 F in summers).Code allows a pan for water heaters - in Florida, we add a pipe from the hole on the side and run it horizontally thru an exterior wall, similar to a condensation pipe drain. 

This involves balancing, tipping, chaining, tipping some more, swinging, and lots of careful hydraulic work on the front end loader of the tractor to get the 18 foot pole from horizontal on the ground to vertical chained and strapped to the forks on the front end loader of the tractor.