If people are going to be that rude and make a big deal that your English skills are adequate, then you're doing the right thing to block them and ignore them. It's really rude for people to say that you can't speak proper English. News Flash: Not everyone in the world speaks fluent English, in fact, there are many people in America who speak English, yet they don't know simple grammar like the difference between "your" and "you're." As far as internet goes, just keep blocking and ignoring people and don't reply back to anyone that is just going to be rude to you. You don't have to put up with that. As for real life, you may be ridiculed now, but as your language skills progress you should do better with talking to people. Like I said before, it's usually very rude and disrespectful for someone to make fun of you because of how you talk. It isn't fair to you or anyone who struggles to speak a language.
I see very little to no difference in English skills in this thread you have showed me aside the current thread that we are on. I highly doubt someone who is a troll would carry on a conversation about Final Fantasy games with another person.
Here's a thought: Ignore it. All your doing is fueling the fire. Not going to lie, it's pretty funny, though. Someone bothers you? Just don't respond and quit getting so angry over other people's opinions.
As for your English, it does need improvement. Instead of whining about how people tell you it isn't good, try actually doing something about it and build your English skills.
To answer your first question, you can't stop people from expressing their own opinions about your english, your art, your religion or anything else in this world. The only thing that you can do about it is ignore it. If you can, hide the comments or block and report them.
Remember that the people who make fun of you for the way that you talk are not your friends. I know that it can be hurtful and irritating but trust me when I say that these people won't be in your life in 10 years time.
If you find that your english is a problem (i.e. you're first language is not english or you have a speech impediment) then taking the time to practice your english could benefit you.
To answer your second question, you can't stop people from abusing you about having two accounts. Simply ignore them or block them. If they continue to harass you then contact the help desk and report them.