TKNY,
You wrote “Yeah, but you have to accept to do them. That does not mean that a Ger who speaks one word of loshon hara is a goy, but s/he does have to be willing to honestly try to keep everything.”
I believe that many hold that the ger must only be mekabel the “ol” of the mitzvos. Meaning he must accept that the mitzvos are binding on himself, even if he knows that it is too hard for him to give up some of his tayvos and that he will be an avaryon.