Credit Analyst comp/promotion structure - is this normal?

Responding to your questions in order. Preface that the degree to which there is a "typical" correlates with the size of the bank. The lower your institution is on the scale, the more idiosyncratic it can/may be because of the personalities involved and the corporate structure. I would expect the following comments to be generally typical for a $200B+ bank. So let that color my feedback for you. 

1. Yes, that is typical and there's good reason for it. If you like this work and want to progress in it; just hang in there. 
2. This will vary institution by institution but your description doesn't sound altogether surprising. I would generally expect the merit increases to be slightly higher in a Corp Banking group than the "community bank" part of the institution but perhaps not that much higher. Once again, if you like this work and want to progress in the industry; internalize the fact that you are going to make your money on variable compensation after you are an analyst. The magnitude of difference between a 3% raise at your level of pay now is not that much less than a 5% raise. 
3. This will vary by institution and reading between the lines, it sounds like your bank might be trying to make it easy and rather than deal with people being butthurt over his or her pay bump - they just have a uniform schedule. That's kinda lame but it is easier to deal with the jockeying that young analysts will do to try and eke out a bit more money. If some analyst in coverage group hears O&G in Houston gets 20% more... then there's talent pipeline issues for everyone except O&G and managers hate dealing with that stuff.
4. The timeline you indicated of 3 years for analyst to associate is generally about right for any junior role. It takes time to learn the bank, the personalities, the credit culture, the processes, the systems; all of it. You may feel like you're ready before then and that's normal. It's also a bit of hubris, which isn't necessarily a bad thing, just be self-aware of it. Don't worry about the normal merit increases at this point in your career. 

Your "feelings" may be somewhat accurate as it relates to doing "more volume" than your peers in the "community bank" but I would caution you against conflating that with "more work". Corporate banking =/= Commercial banking with bigger dollars. If you are looking at pure dollars of production or units of loans that have closed; yeah - you may be doing 5x their volume. But what about the deals that don't close? Corporate banking has a much higher pull through rate than do community bank deals. They may be spinning their wheels on stupid deals that never take flight. The odds are very high that those in-market analysts are saying all the same things about you and other corporate banking analysts having it easy. Tale as old as time. The compensation upside in corporate banking though will far exceed their in-market comp upside over time by an order of magnitude.