[jiang]

Dear teachers,
I have two questions to ask.

No.1

Could you please explain what's the difference between 'to have sb. do sth.' and 'to have sb. doing sth.'?

No.2
The following is an error correction exercise:
That desire fuels your dreams and the special goal keeps you focusing.
The key is to change 'focusing' to 'focused'. Why 'focused'? If 'focusing' is followed by 'on sth.' then the original sentence is correct. Is that right?

I am looking forward to hearing from you.

Thank you in advance.

Have a nice weekend.

Jiang