well my friend youve entered on a long journey... what you've made is was is known as a Cyser
bad news your OG was probably through the roof. oGod news you pinched enough yeast to handle it. Bad news, this is gonna take awhile to ferment out because of the honey and large ammount of brown sugar. Good news your gonna have an ABV when its done of about 15% is you let it go dry.
As for your questions
let primary until you dont see any foam around the top of the cider in the carboy, and air lock activity is low(3-6weeks depending on tempature). Then you should rack off and do a gravity check and then get it back into a carboy. At this point likely you will be around 1.030-1.025... this is still really sweet and it should be allow to sit and finnish for at least a month.
If you dont like this course of action, you can when you've got it so you like the taste of the juice in the fermenter in primary (just take a sample and test with hydrometer and taste) you can cold crash it (get it down below 40F degrees for 24-48 hours) and while its still cold rack into another container off its yeast (you can wash the yeast and save it or get rid of it and put the juice back into the carboy if you want)... because you used two packets of champagne yeast i recamend you do repeat cold crash again. Then after youve racked it you can bottle and still carb if you want.
when bottleing simply check your SG if its stable and no longer fermenting (because of the reduced yeast count from either cold crashing or letting it ferment dry and ageing) add 1 ounce of cane sugar per gallon of cider, or check the ammount of sugar per serving on the back of a bottle of apple juice and add the approite ammount. Example, i use apple juice which contains 28 grams of sugar per 8oz serving, thats 1oz per serving so i add 5 servings (5 cups) to the cider and bottle as normal.
If you cold crash then bottle as stated but after 3-5 days store bottles someplace dark and cool(below 60F degrees) to reduce risk of bottle bombs because of incomplete fermentation. If you ferment dry then bottle and store as normal.
I would sugest fermenting dry, back sweetening with a non-fermentable sugar, and then priming with fresh apple juice. Your ABV will be high, it will age very well, and taste great after about 3-6months... youll thank yourself for your pacients... in the mean time make a few batches with out as much fermentables in them... I recently just fermented straight juice with Nottingham dry yeast, let ferment dry, and primed with apple juice as stated above... the stuff is heven in a bottle in about 4 weeks from start to finnish