I can answer the question about commas vs. semicolons!
Say you have two complete thoughts, such as:
1. Constructive criticism can be really helpful.
2. I wish I got more of it.
Instead of keeping them two, separate, simple sentences, you decide you want to combine them into a compound sentence. You have a couple of choices:
1. Constructive criticism can be really helpful, and I wish I got more of it.
2. Constructive criticism can be really helpful; I wish I got more of it.
In the first example, you would use a comma because you have a conjunction (and) to join the two complete thoughts together.
In the second example, the semicolon just takes the place of the period that would separate them if you made them two sentences. You don't need a conjunction when you use a semicolon.
There are lots of other uses for commas, too, but when joining sentences together like this, the rule of thumb is that if you're using a conjunction (and, but, or, since, so, etc.), stick a comma before it, and if you're not using a conjunction, use a semicolon. Which route you go is just a stylistic choice. In this case, I would prefer #2; I think it sounds better. Some writers might prefer #1. Both are right!
Hope that helps!
