I'll start with the bottom line. Below the line I'll address the specific issues.
Becoming a US tax resident is a very serious decision, that has significant consequences for any non-American with >$0 in assets. When it involves cross-border business interests, it becomes even more significant. Especially if Switzerland is involved. The US has driven at least one iconic Swiss financial institution out of business for sheltering US tax residents from the IRS/FinCEN.
So in a nutshell, you need to learn and be afraid of the following abbreviations:
and many more.
The best thing for you would be to find a good US tax adviser (there are several large US tax firms in the UK handling the US expats there, go to one of those) and get a proper assessment of all your risks and get a proper advice.
You can get burnt really hard if you don't prepare and plan properly.
Now here's that bottom line.
Q) Will I have to submit the accounts for the Swiss Business even
though Im not on the payroll - and the business makes hardly any
profit each year. I can of course get our accounts each year - BUT -
they will be in Swiss German!
That's actually not a trivial question. Depending on the ownership structure and your legal status within the company, all the company's bank accounts may be reportable on FBAR (see link above). You may also be required to file form 5471.
Q) Will I need to have this translated!? Is there any format/procedure
to this!? Will it have to be translated by my Swiss accountants? - and
if so - which parts of the documentation need to be translated!?
All US forms are in English. If you're required to provide supporting documentation (during audit, or if the form instructions require it with filing) - you'll need to translate it, and have the translation certified. Depending on what you need, your accountant will guide you.
I was told that if I sell the business (and property) after I aquire a
greencard - that I will be liable to 15% tax of the profit I'd made.
Q) Is this correct!?
No. You will be liable to pay income tax. The rate of the tax depends on the kind of property and the period you held it for. It may be 15%, it may be 39%. Depends on a lot of factors. It may also be 0%, in some cases.
also understand that any tax paid (on selling) in Switzerland will be
deducted from the 15%!?
May be. May be not. What you're talking about is called Foreign Tax Credit. The rules for calculating the credit are not exactly trivial, and from my personal experience - you can most definitely end up being paying tax in both the US and Switzerland without the ability to utilize the credit in full. Again, talk to your tax adviser ahead of time to plan things in the most optimal way for you.
I will effectively have ALL the paperwork for this - as we'll need to
do the same in Switzerland. But again, it will be in Swiss German.
Q) Would this be a problem if its presented in Swiss German!?
Of course. If you need to present it (again, most likely only in case of audit), you'll have to have a translation. Translating stuff is not a problem, usually costs $5-$20 per page, depending on complexity. Unless a lot of money involved, I doubt you'll need to translate more than balance sheet/bank statement.
I know this is a very unique set of questions, so if you can shed any
light on the matter, it would be greatly appreciated.
Not unique at all. You're not the first and not the last to emigrate to the US. However, you need to understand that the issue is very complex. Taxes are complex everywhere, but especially so in the US. I suggest you not do anything before talking to a US-licensed CPA/EA whose practice is to work with the EU/UK expats to the US or US expats to the UK/EU.