It's unfortunate but the people in countries relying on Ukraine for wheat would have to find their carb from somewhere else. There are many different replacement like rice, corn, cassava, potato, sweet potato and even plantain.
I think the problem here would be cultural and more, they will definitely crave their "daily bread". I'm from a rice country and even when I feel full eating a meal of wheat pasta or bean noodles, I feel that I still need to eat something. This is what they are going experience in the coming months if things don't improve.
Yes - that is correct.
Countries depending on Ukraine for wheat should another source - Also the countries which were depending on Russia for oil and gas supply should find an alternative as well. But do you think it is possible particularly at this time? I think not
Food I think would easier to switch to a different supplier or buy a totally different one (like the alternatives I've mentioned). With oil and gas though it'll take longer to build new pipelines.
This is one reason Russia invaded - the pipelines are already built and Ukraine can use those to export their own gas that has been discovered there - in areas conveniently occupied by Russia now. That would have provided an alternative to Europe.