If we give rates to posts does it makes the money earned in mylot higher?

I am not sure. but I think it should be the same.

yes , rating posts helps in getting more earnings for both the rater & the receiver depending on the legibility of the rating and the quality of the post . And we should not misuse the rating system . we can give a + to an impressing post . it is better to avoid - rating . for e.g. if we give a + for a cheap quality post then it affects in decrease of earnings . And if we give - for a good quality post then that also affects in decrease of earnings . pls see : http://www.mylot.com/o/faq.aspx#useDRS