Greetings DaGwydo,
Blessings to you for considering such a valuable effort. Many in my flock have done what you plan to do, ministering especially in Germany (or nearby Netherlands, France, Sweden, Norway, Denmark or Belgium) so I have some connection to these efforts. Most of them also did their ministering when they had young children at home or were otherwise established, and faced many of the same doubts and challenges that you are. They also prayed over many weeks, sometimes even months or years before deciding, but most of them ultimately did make the move, and the news from them is almost universally positive.
Some things to remember about this sort of mission, both the challenges and the benefits:
1. Unlike many other missions, the First-World nature of a ministry in a place like Germany means that the nature of the personal challenge is different. While you do not have to make major adjustments in coping or lifestyle, missions to Europe are rarely brief. In fact, most of my colleagues ministering in Europe have moved there permanently with their families from the United States, Australia or Canada, with no plans to ever return (aside from occasional visits). In other words, they are in effect citizens of Germany, Holland, France, Belgium or Scandinavia.
2. This also means that they have integrated themselves and their families into their host countries as permanent members of their new homes. The reason for this is simply the nature of the calling and ministry in these lands: often restoring existing churches, sometimes ministering in new ones but still doing so in the context of modern societies with a broader array of influences competing for their citizen's attention. This requires a more sustained kind of mission rather than a brief, in-and-out conveyance of a message, partly by simply increasing attendance in churches where it has been down, living by example and bringing others into the fold who might have been aware only in passing of their heritage. It requires a delicate touch to meet the spiritual needs of people in these societies, which in turn requires full integration over the long term.
3. The practicalities of the mission require mastery of the local language (as well as German which is in effect a common language for these efforts and also in Europe overall for other practical reasons), including raising one's children to communicate in it as integral members of the host society themselves. This is not as difficult as it may seem at first, since being in the local environment constantly makes it natural. But again, it does require a long-term commitment. The same goes for visas, which in general give preference to overseas diaspora in Australia and North America, though work requirements are flexible. So long as you contribute gainfully to the host societies, whether as an educated engineer or basic blue-collar work, you will be accepted and be able to carry out your ministry efforts in the process. (It can also help to partake in activities such as providing patents and opening shops, which can accelerate the visa process in such countries.)
4. Many missionaries in Europe are involved in conversion efforts with the immigrant Turkish, Kurdish and especially Albanian populations. These efforts have been quite successful recently, but they too require a longer-term commitment than in most other countries.
5. Simply planning out your ministry, if you wish to found a new effort rather than (or in addition to) working with the local churches already present, can be an effort stretched out over many years as you become more familiar with your new locality.
So in other words, a mission in a place like Germany requires a long-term and essentially permanent commitment to achieve success. But it is clear that you have thought and prayed about this significantly, so you are in the right track. Speak honestly with your family about it, let them know the strength of your calling, and listen to their contributions. It's not an easy road, but those who have taken the path you are considering have made great contributions to spreading the Gospel, and reached an extraordinary level of fulfillment.
