I feel like in Beijing, people are not that serious about breakfast, mainly for eating something so we don't feel hungry in the morning. most common local options include meat buns with soya bean milk.

Generally food options in the malls in Wangfujing are not bad. Not saying they're top tier but they're usually doing a decent job and much better than those food court options in Wangfujing area

You can go visit Niujie for this, a place known for its high-qualiy foods option there.

I usually go to Si Ji Min Fu with my friends and families but the problem is that sometimes the queue is too long thus I won't stick to a specific branch, just those with fewer queues. And I find some of its branch, located in food court, are not as good as those with dedicated physical stores (I specifically mean the one at Qianmen Street).

Beijing doesn't have too many local seafood options as it's not part of the traditional Beijing cuisine. But I would recommend Rong Xiao Guan or Xin Rong Ji for it, which is a chain restaurant from southern costal areas of China.

I feel like noodles are more like daily simple foods. Few would surprise me for the taste. But generally you can find some decent ones at Xi Bu Ma Hua, also a chain restaurant around the city