the value of opinions.. ..personally id say start off with the bar. I did, finding it much easier to control the kite (being a little slower & a little less responsive on the bar) and ride the board at the same time. I also wore a harness from early on, but only hooked in when i was cruising on a nice smooth run..unhooking to stop, start make turns etc. Now the confidence has grown i fly hooked in 90% of the time, makes for a nicer session too..you can play for longer without your arms falling off.
Id say ive been boarding around 3-4 months now, and learnt pretty much the same way you are..from research, watchin videos & luckily watchin a couple of decent riders @ my local beach.
best bet is just to get out there an see what works for you..take it easy, jus start off steady & have fun.