Student or Learner
I saw this sentence in an article
There are a number of issues that need to be addressed...
Could I use "there is a number ...."
No, don't do that.
"A number of [plural nouns]" means "many [plural nouns]" and should have the plural from of the verb.
In speech, we tend to contract to "There's" even for a plural, but we would not use "There is" uncontracted for a plural noun that followed.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.