grammar - Is it correct to write "offer of" or "offer on" and "whenever suits you better"

I am replying to a job offer and I would like to thank the opportunity given.

I was going to begin my message with:

"Thank you for the offer on CompanyName... "

As part of a response to a message with a job offer I would like to let them know:

"I will be available all morning, so just call me whenever suits you
better"

Is this correct?

Thanks in advance.