I typically go for a brand that is not a "market leader".....So I went with GCC.....My "current" pick would be a GCC Expert Pro for around 1,100 for 24" version with a stand...
As far as software, I like Illustrator but Corel will work just fine.....And if all you are doing is graphics for your cutter a "very old" old version of either will work fine...Great Cut that comes with a GCC plotter will get you by....I do just fine with it, however, others choose to upgrade to better software....
As far as marketing, if you spend a few days reading through the archives you will find lots of ideas.....I do mostly heat press vinyl with my plotter...There are a handful of folks in my area that have polotters but none that have heat presses as far as I know....
Good luck...