1. How do I tax myself as a soletrader with a full time job?
You will need to register for self-assessed Income Tax with Revenue. Form TR1 is the one to use. Your net income (after allowable expenses) from the self-employment will be added to your other income and taxes at your marginal rate of tax. There may also be PRSI/Levies depending on your other income levels and personal status.
2. What tax forms need to be filled out in order to be fully tax compliant,
including VAT?
Depending on your business and the tax heads for which you will be registering, tax forms/filing will vary and each tax head has its own deadlines, requirements. You need to read the relevant Revenue guides on
www.revenue.ie for each relevant tax head for which you will be registered.
3. What books do I need to keep?
At a minimum, cash book recording all income/expenses, probably bank records, cheques stubs etc., all invoices/statements for purchases/expenses. Again, Revenue have guides on these on their site.
While I acknowledge your desire to do this yourself, a consult with an accountant would fill in a lot of other information for you or at the least, a discussion with a friend who is similarly self-employed.
Remember deadlines missed or tax under/over paid, is your sole responsibility. As I'm sure you want to spend most of your time running the business rather than administering it, get it set up correctly from the start and it's much easier later on.
Good luck with it.