Is a letter of recommendation from an employer required to be on the official letter head of the company?
Also is it okay if I give the recommender's personal email?
Nothing in particular is required for a company letter of recommendation. Pretty much any established company will have some sort of letterhead, though, and your recommender using it will feel more "professional." Likewise with corporate vs. personal email addresses.
Regarding personal vs corporate email, I would strongly recommend using the corporate one. If nothing else, because it gives some assurance that the person on the other side is who he claims to be. Would you take this seriously?
I am recommended by the President of the USA, you can find him at firstname.lastname@example.org
Also, consider that in industry, LoR in many countries are just brief cold objective statements:
mihir S worked for Company.inc from 2003 to 2014 in the position of Junior Developer.
But an academic letter is expected to present you as an excellent candidate. Make sure the head of the company understands the difference and is happy providing a strong letter.