Planning to move Europe. Need guidance!!

All these topics are addressed in one form or the other in many existing threads in the forum (https://www.expat.com/forum/viewforum.php?id=303). Please go through the existing information and I am sure you will find answers to most of these questions.

It takes time (and effort - a lot) to read through many threads, research other available sources of information - google helps, compare the information, verify with government websites, research again, and formulate answers for each of these points. I am sure this is something you can do.

Members of this forum are always here to help with more specific questions.

Cheers !

You have posted a message with the same questions about MANY European countries (which I just removed, because it is off-topic in the Germany forum) and also the same in the Australia forum.
Therefore I have to repeat what I told many like you before:
An international move requires real dedication, a sense of direction and special skills that raise you above the locals in your desired country (who would otherwise be preferentially hired).
Thus "any country" will not work.
For Germany (and many other countries on your list) you must ask yourself: How good is your German (or other country language)? Do you like the culture, mentality and way of life there? How well do your skills (education and work experience) fit into the needs of the local industry?
The topics you list are secondary and can be sorted out if the above are o.k.

Like Aneesh mentioned, these subjects have been covered before and you should do the research but I will give a short overview.   

1 Tax rate like in every country is progressive and dependent on how much you make. This is easily googled.
2 Family reunion visa requirements and conditions explained here: https://www.germany-visa.org/family-reunion-visa/

3 This is a long and complex subject often written about. But one has to get health insurance in Germany which pays the doctors and hospitals; you don’t pay direct so your question makes no sense. Whether one gets a public or private option depends on a number of factors. 90% of people have a public option and one can only get private insurance in certain situations. But there are very few private hospitals only taking privately insured patients. Most hospitals are fine and take both. There are advantages and disadvantages to considering private insurance if you are even eligible.  But don’t think the level of care is any worse for having public insurance.

4 Children education is very good, public and mandatory. No home schooling. Some private international oriented schools have English instruction –  if you are willing to pay 1000 Euros a month or more. In public schools the instruction is in German although there exists a few in all of Germany  that have some dual instruction in English; this supports than they learn good English but is not a substitute for needing to know German. 

5 To get an idea of salaries then you should google it yourself since only you know the specifics of your qualifications and skills.