Are you not confusing VAT with your tax liability. If you make a profit, that profit is taxable, so by deducting everything possible, you "reduce" your profit, thus reduce your tax liability.

You will not be able to get a VAT number in advance unless you can adequately prove your turnover to be in excess of 100k within 1 year. Once yoiu get to qook turnover in 1 year, it is for you to apply for a VAT number in Bern; the process is relatively painless.