Translate plotmath expressions

I have 2 issues using function ggplotly in R:

Question 1 What are the ways to keep R plotmath expressions while converting ggplot2 plots to plotly format using function ggplotly?

Now the expressions are converted to [object Object] as in this example below:

library(ggplot2)
library(plotly)

qplot(mpg, wt, data = mtcars) +
    ggtitle(expression(bar(x) == sum(frac(x[i], n), i==1, n)))

ggplotly()

Question 2

How to get rid of double labels in the legend of plotly graph and make them look like in ggplot2 graph? I.e. how to get 6 in stead of (6,6):

qplot(mpg, wt, data = mtcars, colour = as.factor(cyl), fill = as.factor(cyl))

ggplotly()

Start by reproducing both reported examples with ggplot2 and ggplotly: the plotmath title becomes [object Object], and the legend shows duplicated values such as (6,6). Trace how ggplotly converts plotmath expressions and combined colour/fill scales, then verify that expressions render correctly and legend entries match the ggplot2 result.