Fixed the first question with using just CSS:
in map-style.css i put
.gm-style > div:nth-of-type(1) > div:nth-of-type(3) > div:nth-of-type(3) > div:nth-of-type(1),
.gm-style > div:nth-of-type(1) > div:nth-of-type(3) > div:nth-of-type(3) > div:nth-of-type(2),
.gm-style > div:nth-of-type(1) > div:nth-of-type(3) > div:nth-of-type(3) > div:nth-of-type(3){
color:#f04e69 !important;
background-image:url(images/logo.gif) !important;
}
Just the second question is gonna be hard I guess
And is it possible to have a number of posts on the same location?
Like the same idea as the number in the cluster icons.