There are surfaces that it will pit or etch. The instructions are really focused on commercial brewery applications. It can easily be pumped through silicon and seems to be ok with both the steel and plastic march pump heads. You might ask the guys at marchpump.com about it - I am assuming it is fine.
I would NOT let this sit and soak overnight. In fact, I use this regularly with my RIMS system. You only need a few gallons, just enough to be able to pump the minimal volume. Make sure to evacuate any CO2 (say in a fermenter or corny keg) before hand. I add a few ml of Star San for the surfactant. Run it for 20 minutes then let sit (foam will cling to the surfaces helping to distribute the acid) for about 15 minutes. A cold rinse for the same time after. Drain and air dry. Some bicarbonate in the rinse water will make rinsing more effective, but require an additional rinse. It is particularly effective after a PBW soak and light scrubbing, and will passivate stainless. If you have beerstone, run the acid first, rinse, then PBW soak. You will be amazed at what comes off a kettle or fermenter. Rinse well and sanitize with Star San or Sani-Clean.
A couple of comments: Of course, wear rubber gloves when handling and I suggest safety glasses. A little splash will burn on skin - keep some clean cold water close to rinse thoroughly. It will also etch concrete - so dispose in an area where you can let it burn the grass or soil. Make sure to rinse anything it contacts very well. We have fire ants - so they get the spent solution. You can also dilute it further and dispose in sewer. A few gallons of solution in a toilet shouldn't cause problems if just occasional.