u/amp1212 has some great info on the previous threads How did Worcestershire sauce, an English product, come to be so ubiquitous in Japanese cuisine that simply the word for sauce (ソース) can be used to refer to it? and Did the opening of Japan change the Japanese diet and cuisine? Was there a "Perryan exchange" from increased contact with western trade?

This should address many of the things covered in your question. To elaborate on some other points, briefly speaking, Buddhism from China and Korea had a major impact on Japanese cuisine before the Modern period, with the concept of ethical vegetarianism. 7th century Emperor Temmu famously decreed a prohibition of meat consumption during the farming seasons, and later on these would be extended year long. Important to note, different Buddhist sects emphasized different vinaya (Buddhist precepts), and thus had differing views on the strictness of diet. Regardless, because of the value and need of animals for labor and the potential for milk and eggs, and the abundance of seafood, generally speaking meat played a minor role, though hunting on occasion did occur.

From u/amp1212's answer you may read about the influence of Portuguese culture on Japanese cuisine in the Edo Period. By the mid 19th century however, with Japan undertaking its modernization efforts, rigorous globalization and introduction of western ideas were wholeheartedly welcome. American, British, French, and German sciences, militaries, and industry became the model for Japan's development, and we certainly see cultural influences in the late 19th and early 20th century. Western cuisine became fashionable and a mark of modernization and sophistication, and on the aristocratic level European fare became popular. Curry became popularized from the British Royal Navy. Restaurants began to serve yoshoku, Japanese-style Western food, on a popular and affordable level in the late Meiji and Taisho periods, so then we see items such as Ebi Fry, Korokke, Katsu, Naporitan, and Omurice. Post-war rebulding and the American occupation saw imports of canned foods and other items that still shape today's cuisine. Ketchup, corn, and bread were some staple examples of the times.

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This is just a brief summary of a long and nuanced history of cuisine and culture. I wrote an answer a year ago in the semi-related thread How did Asia (specifically the east i.ie China, Korea, Japan) react to the introduction of coffee into their respective commerce and societies, particularly for countries who have such rich culture and tradition surrounding tea., you'll see other great contributions from u/ParallelPain, u/PiousHeathen, and u/p_nerd on the discussion of coffee in Japan.

For more introductionary information, NHK's Begin Japanology/Japanology Plus documentary series aren't a bad place to start, particularily the episodes on Yoshoku, Plastic Food Samples, and Fried Food.

For more scholarly readings, perhaps these are worth looking into:

• Traphagan, John W., and L. Keith Brown. "Fast Food and Intergenerational Commensality in Japan: New Styles and Old Patterns." Ethnology 41, no. 2 (2002): 119-34.

• CWIERTKA, KATARZYNA J. "EATING THE WORLD: RESTAURANT CULTURE IN EARLY TWENTIETH CENTURY JAPAN." European Journal of East Asian Studies 2, no. 1 (2003): 89-116.

• Cwiertka, Katarzyna J. "Serving the Nation: The Myth of Washoku." In Consuming Life in Post-Bubble Japan: A Transdisciplinary Perspective, edited by Cwiertka Katarzyna J. and Machotka Ewa, 89-106. Amsterdam: Amsterdam University Press, 2018.