Certainly notate it on your reservation, but TBH, while there may be little pixie dust things that happen, there is nothing that is designated or mandatory. And nothing ruins little surprises for everyone like people complaining "But we read on the DIS..." (Cast and Crew Members' 6 least favorite words) and demanding the same.
You can always go to Guest Services and get the buttons - you don't have to wait for them to be delivered. The "cake" in the MDR is usually a small, mousse-type thing.
If there is something specific you want - the package with the robes, actual cake, Rainforest Room (which is public, btw...), etc. - and will be disappointed without, go ahead and get it yourself.
The thing is, there are always MANY people celebrating something on the cruise (example: My parents and I were on the Magic in February. During our night in Carioca's, it became ridiculous the number of birthdays being celebrated. We stopped counting after the FIFTEENTH singing of their birthday song. More than FIFTEEN birthdays in one seating in one MDR. Throw in a few anniversaries and other things and the servers were hard pressed to do their regular jobs for all the celebrations. And there were still celebrations in the other MDRs on other nights!) The crew will generally TRY to do things, but again, if there is something you will be sad without, ensure for yourself that you have it taken care of in advance.