Perhaps you could edit the title of the thread to say German American Investing, this would make it more clear what the subject matter is.
Unfortunately as an American living aboard the US tax system considers you to be some kind of apparition that they can't quite understand and it treats you accordingly. I pity your accountant as he tries to sort all of this out. Although he will be amply rewarded for his efforts. I'm a Canadian living in Germany and planning on retiring here so I'm in a similar situation, other than not having to file a non German tax return.
So what I'm seeing you have several issues
1. Where to hold my investments USA or Germany
2. Buy funds or individual stocks
3. Rurup
4. German Real Estate
1. Where to Invest. As an American you are very very limited to what and where you can invest. Generally speaking you can buy stocks and bonds anywhere in the world but for funds you are limited to those that can be sold in the states. Secondly based on personal experience you're better off holding your US investments in a US brokerage, cheaper and better options. For me I have all my dollar investments with TD Waterhouse Canada.
For more information on investing as an American in Germany check out this thread. If you're interested in investing in Germany I highly recommend contacting Starshollow (click on his user name)
http://www.toytowngermany.com/forum/index.php?showtopic=226043. Buying Funds or Individual Stocks A good starting point for ETFs and is Andrew Hallam's book Millionaire Teacher. It's a great beginner investing book. For stocks check out Dividend Growth Stocks or DGS David Crosetti from Seeking Alpha has written some fantastic articles.
http://www.amazon.com/Millionaire-Teacher-Wealth-Should-Learned/dp/0470830069#http://seekingalpha.com/author/david-crosetti?s=david-crosetti 5. Rurup A Rurup is basically a personal Defined Benefit Pension plan. That is unlike an IRA or RSP you have a guaranteed payout at the end, but it also means if you die one day after you retire the money stays with the insurance company (generally speaking). As an American I'm not even sure you can open one.
German Real EstateThere are a ton of misconceptions about German real estate and I could write a very lengthy article about this but for now I'll give a quick summary.
The German real estate market is very very different from the markets elsewhere. First off most investment properties are bought for yield rather than for capital gains, prices have remained mostly flat (with the exception of some areas like Munich) for the last decade. Germans are also long term renters and it's not unusual to look at a property where the people have lived there since the 60s.
Secondly unlike renting in the UK or Canada/US the tenants are responsible for most of the day to day running costs. This includes but is not limited to things such as cleaning the building, landscaping etc. Tenants also pay the property tax (which is much lower than elsewhere).
Rents can be increased by as much as 10% per year but can not exceed the local average. Oddly German landlords are very very slow to increase the rent, so it's not unusual to look at properties where the rent is 50% below market values. Note it is very difficult to kick someone out of a place if you wish to live there.
Culturally it's not unusual for someone moving in to completely renovate the property, this includes painting the whole place, putting in new flooring, kitchen and of course German apartments are built without closets.
Depending on what is written in the lease (leases typically run to 40 to 50 pages) the landlord can make the tenant repaint every 5 years plus upon moving out paint and clean the apartment to move in standards. - On this issue I've seen many many complaints about the landlord coming in with a fine tooth comb and having over a huge list of repairs that need to done before he will return the deposit. Which by the way, up to 3 months rent, which in Munich can mean 3500€ or more.
Also many landlords outsource the finding of a new tenant to a makler or real estate agent, this fee is capped at 2.5 months rent, paid buy the tenant. It wouldn't be to far of a stretch to say that a move could run 10,000€ or more depending on if you have to put in a kitchen.
Generally speaking buying in the right location you can expect yields in the 5-8% range.
Eventually I plan to create a TT (toytowngermany) Wiki on German real estate and hope to submit a guest post to Financial Samurai on buying German Real Estate for Americans.
If you have more questions feel free to drop me a line via TT my user name is Tim Hortons Man.
Rob