You're not asking too many questions - it's important that you understand the information, or it's not useful to you.
You can get a divorce without his agreement. The judge will not force you to continue being married to someone once you have expressed an intent to be released from the relationship. There are things he can do to drag it out - asking for continuances, failing to respond to discovery until you file a Motion to Compel, postponing hearings, etc. However, eventually, you will get a divorce. One of the grounds for divorce
is that irreconcilable differences have caused an irretrievable breakdown of the marriage. If one party thinks the differences are irreconcilable, they usually are - it takes two to tango. Your husband can't force you to try to work things out.
Unfortunately, the length of time depends on how busy the courts are, how proactive you are, what the disputed issues are, and how many things he does to delay, so it's really hard to judge. It could easily take six months or longer just get a trial date. I've seen divorces take a couple of months, but I've also seen them take several years. The best way to tell is to file to get the ball rolling.