Re: Tax Declaration
As a self-employed you can write a letter in advance asking for a delay and if they accept they will tell you that the deadline is by the end of the current year.
Bookkeeping for us self-employed is very simple. You can still have someone do it for you (and my advice is to do so for the first year at least).
Basically keep track of your work related expenses, car repair, mileage for work purposes (in km not miles!!), equipment, paid services (mobile, etc), etc.
No gas expenses because they are considered in your mileage.
If you have an office or home office then add the rent too.
Then make a simple prospect with your total gross income and subtract each voice in your expenses calculating the total. You will include it and use it in the tax forms they will send you each year to fill out.
Of course there are many other things to consider and I would suggest getting help at first so you don't leave anything out and learn how it's done.