Lot of questions! I try to give some answers
earing Miles M&M vs MP
Flying across europe it's much easier to earn miles using MM. In C you`ll be credited 2000 each segment + exec. bonus (25% SEN/ 50% HON) while MP just gives you 125% of the flown miles and no bonus. Traveling intra-german you'll earn 1500 miles in C each segment. Even in Y you get much more miles using M&M.
The only problem is that you get fixed miles flying across europe so if you have a flight with more than 1000 miles MP will creadit you more (e.g. MUC-LIS Q-fare MM 750 miles + Exec. bonus and MP a little more than 1k).
Flying long haul there are many differences. Flying to US in Y using MP will give you much more miles cause of the 100% exec bonus vs 25%/50% with MM. Flying in C you'll earn 200% of the flown miles + exec bonus on MM. The most important difference in flying F which gives you 300% + bonus on MM and only 150% + bonus on UA (300%+50% of flown miles being HON vs 150%+100% being 1K)
Flying long haul to the east MM will credit you much more miles, when not using UA which you won't do starting travel in europe.
It's quite easy for you becoming SEN. You just need 100K miles. Flying 200K (actual flown miles?) will also make you a HON within 2 years (600K in 2 years inkl. exec and class of service bonus), but you need to do all is on LH/OS/LX and some small parnter-carrier metal.
Using the US adress, will earn an discount cert. for an award travel at the end of the year.
If you are sure you can go for HON I'd stick to M&M. Otherwise I'd try to qualify for 1K every year and than collect miles on an MM account when flying across europe.
Hope that helps.