It sometimes depends on the place. I worked at a kennel for a while. It also depended on the time of year & how busy they are.
Usually if you request them to be together, they'll keep them together unless they notice them starting to fight or something.
Blankets - if they brought in a blanket we would usually try to keep it with them (unless we were super busy & unless they kept pottying on it). The less busy the kennel is, the more attention & special treatment they'll probably get.
I would take some of their food too. Otherwise, they'll just be fed whatever food they keep out to feed the dogs with (ours used Science Diet).
Check with the kennel about walking. Some do it for free, some charge you extra.
If you call in advance, they'll usually let you tour the kennel too so you can see what its like before you bring them. Some will let you tour any time & some will ask that you come in between certain times (usually not first thing in the morning, so they have a chance to get it cleaned)
I usually bring something for the workers when I have to take my dogs in for something (like when Gracie was spayed & had to stay overnight). I know that they all love getting something for breakfast - donuts, bagels, whatever. So I took in a box of donuts to suck up a little! lol
I'm sure they'll be fine though. No one can resist cute little chis!
And congrats on your wedding!