I heard that the LL04 Liqui-Moly oil is not formulated for US oxygenated fuel, and will "break down" faster than LL01, and should not be used in the US Market, but should instead stick with LL01. Is this true? Thanks!

Correct, any oil that is LL-04 rated should not be used in gasoline engine in the United States or any other market that has ethanol content in it's fuel. That applies to gasoline engines only, not diesel engines. However, Leichtlauf High Tech engine oil include in this kit is LL-01 approved and is safe to use for the years/models listed in the application guide.

So I live in iowa where the temperatures can get up to 100 in the summer and down to -10 in the winter, I like to drive my e90 328i hard sometimes as well as occasional autocross, but ultimately it is my daily driver, would 5w30 be a better choice or should I go with 5w40, for the first 72k miles it ran OEM 5w30 and i recently swapped it to 5w30 pentosin, I'm not really concerned about fuel economy just wear protection

5W40 or 5W30 are perfectly fine options. At the end of the day this is a multi-grade synthetic oils so it's going to fine for a wide range of temperatures. 5W40 ultimately provides the best protection once the engine is at operating temperature.

Is 5-w40 better to use in a turbo car such as the n55/n54 for better protection in warmer conditions. Or is 5-30 better because it flow better due to tight tolerances in motor and turbo since it’s a lower viscosity ?

5W40 offers the widest range of protection when compared to a comparable 5W30. In our opinion 5W40 is the ideal oil viscosity for N54 and N55 engines. That's not to say that a high quality 5W30 is inferior in this regard but consider at higher operating temperatures it will generally be thinner and offer less protection. N54 and N55 engines generally run pretty hot.

Is the 5W40 weight oil better for weekend track cars?

Technically 5W40 is the most suitable oil for the engines/applications listed. 5W30/0W30 is used from the factory for fuel economy and emissions ratings at the expense of overall engine protection. Regardless of track or street use it's our opinion that 5W40 is the best overall option in these applications.

When I filter for my car (06 325xi) I see a kit for LL-01FE Genuine BMW 5W30 synthetic oil. This kit says it will fit but it has a slightly different weight. Can this cause any issues with the engine? Should I run one through and let it drain to not mix?

Not 100% sure what you're asking. The Genuine BMW oil change kit in question is actually 0W30 (BMW no longer offers 5W30 engine oil). In regards to the N52 engine which is equipped in your BMW it can use anywhere from a 0W30 to 5W40 engine oil. Ultimately, it would not make a difference switching to one engine weight over the other. In regards to topping up which sounds like you're asking about it won't make a huge difference to mix oils but generally would be ideal to top off with the oil currently in the engine. When performing an oil change you can then drain and refill with whatever oil you want as long as it meets specification.

What would be the advantage/disadvantage of the LHT compared to the Syn Tec other than viscosity

There isn't an advantage one way or the other. Both are high quality oils. Only difference is the weight.

According to the manual the oil capacity for my 2011 X3 x28i is 7.4 liters, this kit only contains 7 liters of oil, will that be enough?

For a 2011 X3 the total engine capacity is 7.4 liters but this would be in regards to a dry fill which only applies to a new engine. It's not possible to add 7.4 liters total on an oil change since there is some oil left over in the engine. The refill will use between 6.5 and 6.9 liters of oil. It's best to add 6.5 and top off from there after the oil level has been checked. This kit has enough oil to complete the change.