English question, please help?

if the person you are calling"he" has not come yet,we use the first sentence
if 'he' has not reached yet and the time he has given has passed or he has cancelled than use 2nd sentence.

I think dat u wud rather say dat....I heard that he wud be coming 2day....cuz he's stil nt ***..so its kinda in da future tense....

When I'm writing, I sound much different than when I speak. I write in a relatively formal voice generally, yet when I speak, I sound very very casual. I usually drop the "that" entirely, and I usually use "was" rather than "is". I'm not entirely sure why. Maybe because in my brain I'm subconsciously thinking that heard is past tense, therefore I make all the verbs in the sentence past tense. Just like if someone changed the sentence to start with "I hear that he...", to change the verb to present tense, then in that case I'd probably say "I hear he is coming today."

I'm strange... haha.