People use a variety of words in mathematical writings. The goal of using these conjunctions is to convey as precisely as possible the intended relations between the statements, and so the main criterion that people care about is whether what you write is unambiguous and flows naturally with the thought process. Usually it includes being grammatically correct, but mathematicians definitely won't ignore your work if it is clear what you're doing!
In short, it's not necessary to stick to a precise set of conjunctions, not to say attempt to fix a total ordering on them with regards to priority, unless you are writing extremely formal proofs. There are other far better ways to indicate priority, such as the hierarchy of headings, paragraphs, lines, comma-separated phrases and then phrases joined directly by conjunctions.
Of course, be careful that some terms are already defined to have very specific meaning in mathematical logic, and hence should be avoided in the first place, such as "entails". "Implies" too must be used cautiously. Consider:
If P implies Q, then R.
This is very different from say:
P, which implies Q, and hence R.