i've not eaten at remy yet. i've done this type of dining though and at victoria and alberts etc...
i can tell you this - the portions are deceptively small. i've NEVER been "just full" at such a meal, usually pleasantly stuffed! i know what you mean in terms of things on these types of menu seeming intimidating or down right unappetizing in some way! i wouldn't do seetbreads, although i understand they are great and would probably be great at remys! i havent looked at a remys menu so i assume the things you are listing are there on the menu alone.
first, if you are allergic or vegetarian or something, a menu will be made to you differently. although i've never, and wouldn't ever, say "oh i don't like this" or something (like i don't eat alot of lamb say), often times there may be actually a choice between two courses on a menu. i chose the non-sweetbread one! ha! if i were wsqueamish about something really out there - fish cheeks or something - i would ask my waiter probably and say "wow! i'm afraid!" but part of these kinds of dining experiences is the chefs vision and all that.
i think my advice for the person talking about concerns such as yours would be to jsut go with the flow! a) things are going to be amazing and are created to build on previouses courses b) you will NOT leave hungry unless you ate nothing. and honestly (and respectfullY), if someone (and not saying this is you but i see these kinds of posts come up fom time to time?) is more than momentarily concerned about cost VS volume of food VS likeabilty of food, i would maybe suggest they stick with palos. reason being that you do have more choice etc... i've taken several friends to this type of dining, people who were also concerned along these lines but they went for it! now DH jokes about not getting the truffle course at anywhere nice we go!

also c) if you DID end up hungry and/or hated it, given that you already paid mickey for the cruise, you aren't out as much as you would have been somewhere on land AND there is still food to be had!!!
OMG - we did the 10 course (i think) meal at V&A's "queen room" for our honeymoon and i thought we would DIE.
i hope you go and report bck!