Franz:
"Yes, I know I should get an accountant, but I like to learn how to do these things myself"
I know you wish to learn and do the taxes yourself, however since you haven't filed in 3 years, CRA loves nothing more than getting their greedy little hands into people such as you. everything they say and do will be intepreted as correct, as you have failed to file appropriately on an annual basis. Their are many circumstances that surround the capital gain versus income argument. Having an accountant or CA on your side adds creditibilty to the process and this person can represent fairly in front of the CRA. (if it ever gets to it). It is likely you will be audited so be prepared to provide the doc's of your trades.
Have fun and I do not envy you at all.......Fast