Negative-imperative for 形容動詞 and 形容詞

Question

For verbs, we can use it's te-form to make imperatives and negative imperatives, such as:

走って！ 走らないで！
Run! Do not run!

Of course there's also 走れ！ and 走るな！

For 形容動詞 and 形容詞, however, I realize that I actually don't know how to put them into negative-imperatives. What I have been using all along is to use する:

Affirmative: 早くして！ Be quick/early!
Negative: 早くしないで! Don't be quick/early!
Affirmative: 静かにして！ Be quiet!
Negative: 静かにしないで! Don't be quiet!

However, I know for affirmative of 形容動詞 you can use it's te-form as well like this:

形容動詞：みんなお元気で！ Everyone please be 元気！

My question is:

1. Is using する, like demonstrated above, the most proper way to make imperatives of 形容動詞 and 形容詞, both affirmative and negative?
2. Are there any ways of making imperative without する for 形容動詞 and 形容詞, like the お元気で！ above?

(Is this even right?)
早くて！　Please be quick!
早くなくて！　Don't be quick!
密かで！ Be secretive!
密かじゃなくて！ Don't be secretive!

Answer 1

Adjectives don't have an imperative form, so you basically need to attach some verb to express a command or request (しろ/して, いろ/いて, 来い/来て, or whatever). But the verb can be omitted if it can be inferred from the context.

So "早くして!" and "早く!" are roughly the same, but "早くて!" is incorrect because I cannot imagine what imperative form can follow it. "お元気で!" is common as a shorter version of "お元気でお過ごしください!". "簡単に!" can be "簡単に言って!" (Say it more simply), "簡単にして!" (Make it simpler), etc.

When a negative imperative or request is necessary, you simply say the corresponding verb explicitly. "早くしないで!", "元気で過ごすな!", "簡単に言わないで!", "簡単にするな!", and so on.