For the first one, depends on exactly what you're looking for i.e. "make custom transfers". Are you wanting someone to produce the printable file for you? Someone to print a printable file? Someone to do the whole thing start to finish?
For the first question, it's a matter of finding someone willing to do the design work for you (some willing to do it for free; others for a fee). For example, I've created a number of decal files over the past year (see the
Downloads section over on B&C), and usually do the design work for free (had a period where I charged model bits for private commissions, which netted some nice parts).
For printing services, see the Custom Decal Companies in
this thread. It's divided by country, though the list is second hand, so no telling which of those companies are still in service, if any.
For one-stop-shopping for custom decals, check out
Fallout Hobbies. They completed a Kickstarter earlier this year, and are nearing completion of their
KS fulfillment.
And, as DarkKnight44 said, there's always the self-print route. You can find info on that in
this thread. The two keys to remember are 1) get the right paper for your printer type (laser for laser, inkjet for inkjet) and 2) get the right style for the job (clear vs white paper).