The dividend tax credit is not applicable to foreign dividend income, so you would be taxed fully on every dollar of that income. When you sell a stock, there will be a capital gain or capital loss depending on if it gained or lost value, after accounting for the Adjusted Cost Base. You only pay income tax on half of the amount earned through capital gains, and if you have losses, you can use them to offset other investments that had capital gains (or carry forward to offset gains in the future).
The dividends from US stocks are subject to a 15% withholding tax that gets paid to the IRS automatically when the dividends are issued. If the stocks are held in an RRSP, they are exempt from the withholding tax. If held in a non-registered account, you can be reimbursed for the tax by claiming the foreign tax credit that you linked to. If held in a TFSA or RESP, the withholding tax cannot be recovered. Also, if you are not directly holding the stocks, and instead buy a mutual fund or ETF that directly holds the stocks, then the RRSP exemption no longer applies, but the foreign tax credit is still claimable for a non-registered account. If the mutual fund or ETF does not directly hold stocks, and instead holds one or more ETFs, there is no way to recover the withholding tax in any type of account.