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!
You will have to submit on your income from the business. The term "partnership" refers to a specific business entity type in the U.S. I'm not sure if you're using it the same way. In a partnership in the U.S. you pay income tax on your share of the partnership's income whether or not you actually receive income in your personal account. There's not enough information here to know if that applies in your case.
(In the U.S., the partnership itself does not pay income tax - It is a "disregarded entity" for tax purposes, with the tax liability passed through to the partners as individuals.)
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!?
As regards language, you will file a tax return on a U.S. form presumably in English. You will not have to submit your account information on any other form, so the fact that your documentation is in German does not matter. The only exception that comes to mind is that you could potentially get audited (just like anyone else filing taxes in the U.S.) in which case you might need to produce your documentation. That situation is rare enough that I wouldn't worry about it though. I'm not sure if they'd take it in German or force you to get a translation.
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. I also understand that any tax paid (on selling) in Switzerland will be deducted from the 15%!?
Q) Is this correct!?
The long-term capital gains rate is 15% for most people. (At very high incomes it is 20%.) It sounds like you would qualify for long-term (held for greater than 1 year) capital gains in this case, although the details might matter.
There is a foreign tax credit, but I'm not completely sure if it would apply in this case. (If forced to guess, I would say that it does.) If you search for "foreign tax credit" and "IRS" you should get to the information that you need pretty quickly.
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!?
Even in this case you will not need to submit any of your paperwork to the IRS, unless you get audited. See earlier comments.
