I'm not sure I'm following all your issues, but I'll address a few things I see.

First, I would not mix cabinet brands within a piece, if that's what you're saying in that last part. That seems to tempt fate and ask for problems. I'm more non-matchy than most, but that goes too far for me to want to try it (you'd have to deal with differences in construction, differences in finish, possibly wrap the IKEA in another brand's panels -- sounds like you might wind up spending more and not getting as good a result. I'd rather figure out something creative or add them later if I had to. But what do I know?

Second, have you looked for ready-made or salvage/resale islands or cabinets that could become islands? Even resale cabinet bases from a kitchen display? Same for the hutch -- you might find a piece that fits your needs ready and waiting for you.

I see a problem with what you are thinking on the island layout if you select all your cabinets. Your bookshelves onthe back will likely be 12" or so deep, but the cabinet and drawer are likely to be 18, 21 or 24" deep.

In case it helps, my island sounds like it is a little longer, but it has a 24" drawer, a 15" trash pullout and a 30" sink base -- all 21" deep. The back side are 2 13" deep cabinets with doors and shelves (like an upper). Across one end, we put a 10" deep open bookcase. My hutch has 15 " drawers on either side of 24" drawers (fridge drawers, in my case). The top has 15" cabinets stacked above shalow drawers that fill the space between the usual upper and the counter. There is an open bookshelf with a valance in between the two uppers and a crown across the top. We put leaded glass in the upper doors.

If you are trying to match existing cabinets, I would work with the same manufacturer or a dependable custom builder. And keep in mind that older cherry will likely have darkened and matching over time is going to be difficult. Consider painted or a noticeably different finish and style to go with instead. My island and hutch are both knotty cherry, and I really like the old furniture feel with it. I would also consider paint or colored stains to get a different look and furniture feel. If you are going to do something different, make it decidely different and not just enough to look like a mistake or a later addition that didn't quite work.

Good luck --- always lots of things to think about and sort out in any kitchen.

Here is a link that might be useful:

Of course you can do exactly what you want with stock sizes. For your hutch, consider a 36" wide by 24" tall over the ref cabinet between the two tall cabinets. A lot of manufacturers have will this stock in wall cabinet depth.

Nine cabinets plus moldings and finished ends ought to get you by order minimums.

The real problem might be that even new omega's aren't going to match for color. Cherry changes color when exposed to light and your new ones aren't going to match the existing ones for a long time. I supposed you could try cooking them with a tanning lamp :)

I think I would choose to make them intentionally different, perhaps painted. Don't forget that Schuler and Medallion are the same company and share many doors and finishes. You can get a quick drawing and estimate at Lowes.

I think you will run into problems trying to mix pieces of cabientry from different manufacturers - and incur extra labor costs to make it work that may offset some of the material savings.

If I were you, I would stick with one source for the cabinets. Also, as others have noted, matching your cherry may be difficult. If it works in your design, I would get the island cabinets painted the same color as the hutch you plan

Some of the specialized pieces frequently used in islands can be budget-busters! Things like furniture legs, feet, interior finishing, finished end panels, beadboard, apron strips... You can generally find those pieces online direct from the fabricators and unfinished for a fraction of the price, but then have the challenge of trying to match them up with the stock cabinets.

If I had a do-over, knowing what I now know, having learned the hard way (but with a successful result) -- I'd have had the island custom-built. Since you're willing to have a different finish for that piece, look at having just that piece custom built. It'll still be high - but probably lots less than having the cabinet company do it.