Not an issue. Most here aren’t native and even those who are oftenly can be a bit odd when it comes to grammar and such. Myself included. Your English will get super good, trust me.
Give this a read. Also install an addon called “Total rp 3”. It will give you a small profile to fill out, others will see that profile as well as you being able to see others profile.
I’ve seen people who started having zero knowledge at all. There might be the odd one out, but you can in said addon give yourself a little badge that tells others you’re a beginner.
I don’t know any on the top of my head but I am sure people will post their guild stuff in this thread. Plenty of guilds do and are ready to assist you with learning roleplay.
In the TRP profile you can write that you are new. Although I suspect you were more meaning in character? Maybe try a simple role and a more simple race to portray. Just to get the hang of it.
Yes.
Whatever race you choose to play, you should know some basics. Like for example a human probably knows that Anduin is their king. Very basic stuff. You don’t need to be a lore wiki in character. It’s important to know some general things though. But it really does depend on the race. A gnome would know about what happened at Gnomeregan, a blood elf what happened to Silvermoon and so forth.
I can also recommend just walking a bit around in Stormwind with a TRP. Read other peoples profile, watch how they play and stuff. You’ll get the hang of it eventually.