Wow- lots of questions in such a short paragraph! Here goes-
Well, if you still have some lees, I'd recommend not bottling yet. Otherwise, you'll have sediment in your bottles. I'd say to rack and if there are no lees in 30-45 days, then you're set to bottle.
I use 1 campden tablet per gallon every other racking, and at bottling. If you haven't yet, I'd say rack and use the dissolved campden and let it sit as above.
Do you want to sweeten a bit? I like my blackberry dry and oaked, but it is a matter of preference. If you want to sweeten, you'd have to rack, sorbate and campden, and wait a week or two. Then, sweeten to taste and bottle.
To prepare the bottles, sanitize like your beer bottles but no need to do anything with the corks. I feel like I "have" to sanitize the corks, so spraying sanitizer on them is what I do. Do NOT boil the corks! As far as how far down they go, you push them all the way in, or just slightly below the lip. I like mine level with the top. My corker took a few practice tries before I got the right depth, so I recommend you practice a couple of times with the same size bottle and cork. You fill the beer bottles and wine bottles the same way- the bottling wand makes the depth correct. Then, leave them upright for 3 days. This allows the cork to fill out the rest of the way after being compressed to go in the bottle. After three days, store on it's side to keep the cork moist.
Did I answer them all? If not, let me know. I've had a few tonight and even though this makes perfect sense to me right now, I might be able to improve if needed!