@(Cite Contribution)
You've touched upon 3 things:
a) Broken and incomplete sentences:
Now, that's not always a negative. Infact, one of the major differences between written and spoken communication is acceptability of half sentences in spoken communication especially in casual, semi-formal or peer to peer communication. For example, look at the following exchanges:
Exchange 1:
Director: Why have we missed the project deadline?
Manager: "The HR policies! We spent so much time implementing them that we didn't have enough time for the project"
Exchange 2:
Director: Why have we missed the project deadline?
Manager: "We have missed the project deadline due to the HR policies! We spent so much time implementing them that we didn't have enough time for the project"
Exchange 1 is more natural and conveys the message better precisely due to the incomplete sentence.
Of course, you wouldn't want to use incomplete sentences in mails and documents. While speaking, you might want to be a little cautious while using half sentences with the boss. Apart from that, I think it only signifies your higher comfort level with the language and fluency. Yes, it's actually an asset.
b) Reading aloud
It can be pretty useful because hearing yourself gives you a feel of how you sound and also exposes many of your mistakes.
Another aspect is that reading aloud slows you down and gives the chance to your mind to get distracted. So, a happy medium is to read 1 or 2 pages aloud and if you need to do more reading, do it silently.
c) Being brief can be taken for being arrogant
Very good point. Giving long explanations may sound more polite.
However, in business, you are expected to be economical with words - sharp and to the point. Being pithy signifies confidence and if that is matched by your work, you are on a royal road to power and super stardom in your company.
Of course, if every time someone asks you a question, you utter only single word answers - you'd sound like a rock and roll crazy teenager.
I think the best strategy is to see the kind of impact you are having on people. Half sentences as such are not bad, infact, good if you are not overdoing it. See how people react and see if you reply 100% of the times in half sentences or just 20-30%. Therein lies your answer.