Employment letter or I-864

I am primary applicant, and on EB immigration. My hu*****and is working.
1) Does my hu*****and needs affiditive support?
2) Which I-864 form to use to sponsor my hu*****and?
3) If no need the I-864, can my hu*****and provide an employment letter from his company?
4) What should be included in his employment letter, will it be the same format as my employment letter?

Thanks _:$ _:$