Based on what you described, there's some major flags you must get answers for and must do things right to avoid unfavorable taxation to the potential tune of thousands if not tens of thousands of dollars. If your current accountant can't answer these questions, get a different one even if it was already a headache to get your current one. Don't skimp on this, it'll cost you many times more than the $1K ish it will cost to get a proper accountant or one at a big 4 firm.
1. Because you are a corporation contracting for a single client, you seem like you have a high chance to be considered a PSB. This limits your ability to deduct things including the accounting fee and has unfavorable tax implications to you. As a PSB, you basically can only deduct your wages and your benefits against the contracting fees you charge.
https://www.canada.ca/en/revenue-age...-business.html
Talk to an accountant and figure out how to do additional work and obtain additional clients to avoid being considered a PSB.
2. Compensation wise, rule of thumb is likely you want to do management fees and salaries (tax changes in last 5 ish years affected dividends). Dividends are likely going to have leakage causing you to pay more taxes and have less cash in pocket once it reaches you personally.
3. Keep a detailed mileage log or pay for an app that can do automatically track it for you. Otherwise, if detailed logs aren't maintained, you may not be able to deduct vehicle expenses. But as a PSB, you can't deduct these, nor office expenses, nor accounting programs etc.
4. Investments wise, due to changes in tax rules in the last 5 ish years. Rule of thumb is to keep them personal. Don't do a substantial amount in your corporation.
The PSB situation you have is ####ty. Make sure your accountant has the expertise and willingness to help you navigate the issue.