helou, Yes you are correct. I needed to first rip the boards from their original 4 inch width, down to about 3 inches to fit in the drawers. (or about 1 3/4 inched for the front section of the silverware drawer. Also once I had the boards the correct width, I needed to carefully cut the boards to length. Then to get the boards to the correct length a powered miter saw is the best option, but again depending on what tools you have available, maybe a hand-held circular saw and a speed square, or a miter box and a hand-held pull-saw. If you have a table saw, ripping the boards is trivially easy. If not there are probably a number of other ways to make the boards the correct width. (The easiest might be to find a friend with a table saw, and ply that friend with a bottle of wine, to cut them to width.) But you should also be able to do it with a straight-edge and a hand-held circular saw, or maybe even a straight-edge and a utility knife.

Those are from Ikea, part of their Rationell line. I looked for them online but didn't see them, maybe someone more Ikea savvy can say if they still make them or not, I don't get there too often. They are nice though, attractive and flexible, and inexpensive! There were two sizes when I bought them, these are the larger.

Wood hollow. See the recent thread linked below! Here is a link that might be useful: Thread on wood hollow inserts

In addition to the extra flatware trays, you'd need extra cutlery drawers. It's very unlikely you'd completely empty a cutlery tray before you need to replace it with the next tray of clean cutlery. You'd be forever shuffling cutlery from one tray to another to make room for the next tray coming out of the dishwasher. Before long, you wouldn't know in which drawer various pieces of cutlery were stashed. A totally impractical idea to my way of thinking. Don't get me wrong, though. I'm a big fan of the cutlery tray in my Miele dishwasher. I load it with all the forks in one area, the knives in another, spoons in another, etc., etc. I also segregate stainless from silver. Once the machine is ready to empty, it's a simple matter to gather up each type of utensil and put it away in its respective slot in the cutlery drawer.