yet another carbonation query

Thanks in advance to all the experienced ciderers out there who are helping out us newb autumn appleheads--here's my story. So a few weeks ago I picked a load of apples, crushed 'em in a big old press, and deposited them in five gallon carboy (unsanitized, of course). After a few days I added a vial of liquid ale yeast--in my ignorance I neglected campden tablets or anything to calm down the wild yeasts that were already working away. Anyhow, the ale yeast took over and now, a few weeks later, the cider is clearing significantly, and is down below 1.000 on the hydrometer, but is still slightly active and just a bit fizzy--there's about a 1/4 inch loose layer of bubbles on the surface. It tastes decent--tart and appley--with a slightly gross yeasty/bready aftertaste, which appears to be diminishing over time. I'm guessing it's about time to rack to a secondary, and here are my questions...

1. I'm concerned that the continuing yeast activity (which appears to be slowing) is not the ale yeast winding down but some other wild yeast waking up now that the ale yeast has run its course. Is this likely? I'm satisfied with the ferment and don't really want it any drier, or worse, vinegar--so I'm considering knocking it out with some campden or sorbate or both. Is this a good idea? Are my worries legit?

2. And now on to the title of the post...Carbonation. If I do knock the yeast out with campden, can I still bottle carbonate (I don't have a keg) after a few weeks in the secondary? Would a re-pitch be possible, or would I risk exploding bottles?
I know that brewers some bottle-condition high gravity beers with a second pitch at bottling time, but I've never experimented with that.

Anyway, thanks for anyone who took the time to read my post--this forum is really fine!

proton

As soon as the yeast you pitched has run its course, there'll be nothing left for the wild yeasts to eat- all the sugar will be used up, so there's nothing to worry about there.
If you throw in a campden tab or some potassium sorbate that'll kill off any yeasties or bad bugs that might be swimming around in the cider. To get things fizzy again, put a small amount of sugar in the cider and a few grains of yeast and bottle it. that'll create a small amount of fizz for your carbonation needs without creating "bottle bombs."

thanks, odin

should I prime it like beer--half cup o' corn sugar per 5 gallons?

You can stop the ferment with campden, but if you add more yeast & priming sugar, the new yeast will finish fermenting whatever are left in the cider. You'll end up with a dry cider, unless you chill the bottles once they carbonate. This is always tricky. A half cup would be right. I'd chill after a week and check a bottle for carbonation vs. dryness.

That sounds like a plan. I'm honestly not worried too much about dryness, more about vinegarization (does that really happen?)