Translation:I will eat beef for dinner.
The culinary definition has many rules and exceptions. Generally meat from mammals (for example cattle, horse meat, bull meat) and meat from hunting (wild boars, deer, pigeons, partridges, quail and pheasant) excluding fish and insects are considered red meat. Although poultry is usually considered white, duck and goose are red. For some animals the culinary definition of red meat differs by cut, and sometimes by the age of the animal is when it was slaughtered. Pork is considered red if the animal is adult, but white if young (e.g. suckling pig). The same applies to young lamb and veal. Game is sometimes put in a separate category altogether. (French: viandes noires — "dark meats".)
Pork is considered white under the culinary definition, but red in nutritional studies. The National Pork Board has positioned it as "Pork. The Other White Meat", profiting from the ambiguity to suggest that pork has the nutritional properties of white meat, which is considered more healthful.
Clearly there's no good reason to translate 牛肉 (ぎゅうにく) as "red meat".
Technically, no. 夕飯、夕食 and 晩ご飯 share the same kind of nuances dinner, evening meal and supper have. As far as I can tell, ばんごはん sounds the roughest, followed by ゆうはん, followed by ゆうしょく. As you learn more kanji you realize how some are used predominantly in language that sounds more polite.
Is there a reason why に is used here and not で? From what I understood, they're both used to describe a verb in a certain place, but the former is usually used for the existence verbs, not the action ones.
It's also used to describe a time, but one of the other questions had きのうのゆうはんでは, which is also technically a time, so I'm confused as to how this works.
I'm not sure which question you are referring to, but I can't imagine a scenario where "昨日の夕飯では" would work as a time marker. One of the functions of に is the time marking particle, which is a function that で doesn't have. This is what the に here in this sentence is doing.
As you mentioned, に and で have a similar function in marking locations as well. However, using で means that the action occurs at the word marked by で whereas に doesn't have that meaning. に marks important information about the location still and is sometimes analogous to "in" or "to" in English. で has more of a "at" feel, but these aren't a one-to-one translation of the particles. Examples to follow:
私は公園に行きました。(I went to the park.) 公園で食べました。(I ate at the park.) 9時に家に戻りました。(I returned to my house at 9.) 公園に大きなプールはあります。(There is a big pool at the park.) でもそれ代わりに私は自分の風呂で泳ぎました。(But instead, I swam in my own tub.)