No worries on the Mobil oil, that one is fine.

You can use the Iridium plugs, but not sure what you are trying to save here. You are better off with OEM.

I wouldn't use a Fram filter, all filters are definitely not all the same. Whether or not it is made in the same country or factory as an OE filter is irrelevant. What you should care about is the filtering efficiency, and the pressure drop. Many filters from the same manufacturers use different filter media, and different assembly methods. Fram is a Walmart grade filter, not an OE grade filter. Great choice for an older North American vehicle. Unless you have specs on both the Fram and OEM filter, you are much safer using the OEM filter. The K&N filter is available in two styles, a wet filter (the one with the oil on the filter media) and a dry filter (samed style as a Fram). This is a part you only buy every 100,000 or so, so suck it up and just spend the money. Presumably you are doing this work to make your vehicle run longer, so putting inferior parts in is counter-intuitive.

You can do the fuel filter if you like, but what problem are you attempting to solve? Do you have fuel starvation issues? Whether or not you use premium fuel doesn't matter, it is whether or not you use clean fuel. Premium is often not as fresh as regular, as it can sit in the distributor's tanks longer, so more often than not a vehicle using premium from smaller stations will clog up a fuel filter before one using regular from the same stations.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue