cost of housing in Switzerland can be deducted, can you practically do this?
Question 2:
My agency offered that they'll be paying taxes on my behalf and make accruals for vacation, is that the only option I have? Given that I will have to file a tax return anyway based my salary bracket, can I do just this without paying withholding tax/vacation accruals?
1. No, as you won't be an "expatriate" for the purposes of receiving expatriate expenses.
The second paragraph of the link you provided tells you why it doesn't apply in your case.
2. No, you have to do it the way the agency/payroll company offers it. If you don't like accruing the vacation days ask for them to be paid to you each month whether you take vacation or not.
I can prove it indeed, my wife will stay in that property on a frequent basis I'll be staying there occasionally maybe once in 2-3 weeks initially. While proving the mortgage is easy, what in considered a proof of me not letting it in practical terms other than my assurance?
Could I get a link to the official document declaring this (would be also great to understand what "reasonable" term mean - is 3K monthly rent in Zurich reasonable for 2 people)?
The only option being tax at source, correct? I heard some people on this forum either started from not paying withholding tax or paying it for a few months initially and then got refunded and switched to use tax returns, is it possible, can I ask for this to be implemented from day one?
Is taking a months vacation compulsory in Switzerland or I can opt out of it? I'm a experienced contractor and well used to taking holidays at my own expense.
I believe some companies insist on two weeks in one go but as a contractor here it's highly likely you'll be able to manage it yourself like you've done previously. Mine was never restricted or controlled other than negotiating with/informing the client each time.
As an employee you'll end up paying insurances and pension that you might not be used to doing but it is worth considering insurance for if you become seriously ill and can no longer work, especially if you plan to stay here. These things you need to discuss and negotiate with your agency/payroller.
Ask your agency, I think in general they stopped offering to pay it out but it's probably not mandatory. At worst they can pay them out when your contract expires and you haven't taken them.
This category does not include foreign employees who are employed by Swiss employers.
So sorry, OP, no housing expenses for you - at least under this rule. You might like to employ a local accountant to do your tax return for you. I'm sure they'll find some deductions. Mine did.
Unless you are married to a Swiss national, are a permanent resident or are Swiss, you will be taxed at source - and earning over 120K you will also have to fill in a tax return.