JP:
I have an Epson 9600 44 inch wide format printer which I use for printing my own work on paper and canvas, fine art prints for other artists, large photographs for a few local photographers, and occasionally some indoor signage.
You have two main classifications of printers. Water based and solvent based.
The Epson and new Canon WF printers are water based and are excellent for the uses I described above.
Solvent based printers are another matter all together. These are excellent for outdoor/long term signage, but typically, they are not used for photo or fine art repro work.
The two types of printers also represent two VERY different businesses and they should not be confused with one another.
You can do "some" outdoor signage and back-lit work if you are willing to get into lamination and mounting, but as I said, this is typically the domain of the solvent printer.
Art repro work is again very different from photo printing. You also have to look into how you will handle image capture of the original. Most people like myself do offer this as a one-stop service, but there may be someone locally for you that can do that part of the job. Reproducing original artwork does require a considerable learning curve, not to mention additional financial investment.
You can do okay keeping to portrait work, larger photographs and limited signage and tradeshow posters, but therse are typically not high volume production machines so don't expect to be cranking out hundred of items at a time. Don't even think about doing less than 8 x 10 as you cannot compete with Walmart, Costco, etc. with these machines.
If you have the skillset, you may also consider offering photo retouching and restoring as well. It can be quite rewarding.
If you have any other specific questions, feel free to email me.
HTH