How to use, will, will be doing, be doing, be going to do ?

Oh! really!!
I guess many English learners are confused with that!
Some book says that "will be doing" is more polite than "will do".

And, if I say
"I'm playing baseball"
Can you understand what I am doing NOW?

I think I may be playing baseball now, but I may be cooking, or doing nothing NOW.

Yup, since you used "-ing" you can understand that you're doing it now. ^^

Thanks again ^^
huum, let's say...

You heard me saying,
"I'm playing baseball"
when I was talking on the phone with my brother.
and before you heard it, he asked me about what I will do on next Sunday.
So, I'm playing baseball on next Sunday.

I guess you need additional information to know correct tense when I use "be doing" like on next Sunday.
And of course, if you saw me, you would say "You are talking on the phone".

That also makes sense :) You're right, you would need more information, but for most situations, you could use any of these phrases. ^^

thanks ^^
I finally understand it.