If you use the "search engine" on the Forum, you can locate all sorts of wonderful information that will answer your questions. Try to be reasonably specific such as "fleece liners" or "kitchen area", etc. There are also many pics in the Gallery of very creative cages. I highly recommend that you spend a couple of days just reading through previous posts to get up to speed.
A kitchen area can mean different things to different individuals, but it generally means a separate area for hay, food, pellets and water. Some folks create this on the main level, but mine is the loft area. I'll post a pic below so that you can see how I designed it. There is fleece on both levels with an addition of a litter box in the loft. The loft contains the litter box, pellets, hay rack, and water bottle. As you can see in the pics of the cage when if was first built, I tried adding a small litter box on the main level. Chester would have nothing to do with it until I put the large one in the loft. They really need room to turn around and find a comfortable position.
Many people don't sew their fleece liners, but it is really worth the time it takes IMHO. I made three sets of very good quality liners a year ago, rotate them weekly, and they are barely showing any signs of wear. (I'm not the person to comment on using fleece without being sewn into liners to fit the cage because I wouldn't even consider it.) My liners are two layers of fleece with a layer of uHaul pad in the middle. If uHaul pads aren't sewn into an enclosure, they will begin to disintegrate in the wash. Under the fleece liners, I use puppy pads that I buy for a very good price at Ocean State Job Lot.
I have one cavy who is almost totally litter box trained and one who is only partially trained. Chester pretty well trained himself (with a little help from Mom) and will get out of his cozy, go up to the loft, use the toilet without snacking on anything, and go back to bed in the cozy. He's such a delight! He did a pretty good job of training baby sister (Maya) by example, although she still doesn't always make it to the litter box. We're hoping that she will get the hang of it as she gets older.
I'll post a couple of pics, but keep in mind that the one of the entire cage was when it was first built. The pic of the loft in use is more recent and will give you an idea of how it is used.