I am planning to mix top soil and cow manure with 1:1 ratio and use for growing vegetables, flowers, plants in a plastic container/pot. Will the plants grow well? I will be using fertilizers for the plants with NPK 16-12-12 as per the recommended usage in the pack. Will the plants grow well?
The answer is "maybe." You don't say whether the cow manure is well aged (composted) or whether it is new, and it's important that it be aged for it to work with your plants, as explained in this article: Turn manure into compost for your garden
When properly used, manure eliminates the need to apply chemical fertilizer, since they both supply, but in not exactly equal amounts, the three major nutrients needed by plants: nitrogen, phosphorus and potassium. Here is another article specifically devoted to fertilizers: Fertilizing Your Garden
Finally, you might find the information in this OSU publication helpful: Growing Your Own (EM9027). It covers everything you need to know about vegetable gardening in the PNW. Good luck!