なにか can mean something as well as somehow while なんだか is always the adverb somehow. なんか is a less formal, more colloquial version of なにか with its に changed to ん (cf. 撥音便)
Although だ should be etymologically the copula, but as you can see in the link, it would be simpler to consider them as independent words on their own.
なんだか悲しい気分だ = なんか悲しい気分だ ...
なんだか is three words なん + だ + か but it's become a set phrase and is used as a word itself pretty much to express an idea like somehow, somewhat, or rather.
It's rather cold today.
なんか is different with a couple of different uses. It's usually an informal version of なにか or など.
I want something cold to drink.
は does not mark the subject; it marks the topic. The topic can serve any other function in the sentence. Often the topic is the subject. But, it can also be the object (direct/indirect) of the verb. は also can be used to mark contrast.
Notice, the topic is actually 値上げ, the increase in price.
With 東京電力では, the use of は adds a sense of contrast. Various ...
The short answer is that both meanings are applicable and the only way to know is from context.
The problem here is that in spoken language, なに tends to be shortened into なん, such that the two meanings "by what means" and "for what reason" overlap. If one wants to be clear, one should say なにで when referring to "by what means", ...
Both are possible but in (subtly) different contexts.
Roughly 普段に means for non-special occasions, daily uses and its implication is that something different is used for special occasions. 普段は means usually, with implication being that the speaker is doing otherwise for some reason.
普段に(1) means I wear this sweater for non-special ...
In Japan, when you use the word "勝負" with "もらう" it means
この勝負は僕が貰ったね。"I've got this game, haven't I?
Or...この勝負は君にあげるよ。"I'll give you this game."
These phrases are common.
この勝負、私にくれる？ "Can I have this game?
It is also common to say.
However, except when you say things like these, you don't say あげる, もらう, くれる the ...
One common reason to say じーっ out loud while staring at someone/something is to intentionally signal what you are doing. Its implication depends on the context, but it's typically something like "I've been watching you", "Are you serious?" or "I'm interested in this". This is a bit childish act, but that is not to say adults ...