I'm late to the party, but...
For labeling, when I use the swing top bottles I got some 1/2" round labels to put on the lid. You have to write small or use shorthand. I've also just printed up labels on plain paper. Cut them to size and glue them on with a glue stick. The beauty of this is they wash off with nothing but plain water. Not good if you have different brews in a cooler of ice, though.
For carbonation, I like to stick to using the sugar that produced the alcohol. So when I brew beer, I use dry malt extract. For mead, I used honey. The few times I made wine, I didn't carbonate. If I ever do cider, I'll probably leave them still, but if I carbonated, I'd probably use apple juice concentrate. It may be in my head, but it seems like it makes things taste more "pure" to use the same sort of sugars.
Vilkas, the only advice I can offer is what's been told to me in the past. It is much easier and safer (i.e. no bottle bombs) to ferment dry and bottle, then sweeten in the glass. Since you want it sparkling, I'd prime it like I'd do any beverage and sweeten it at time of consumption. Just add a little simple syrup to the glass before you pour the wine.
