If "Christianity" were monolithic, and if it were possible to understand each questioner's situation, and if we could ensure that only qualified people answered, then yes, it would make a lot of sense to start allowing these questions (or start a new Stack Exchange site for them).
- "Christianity" for the purposes of this site is not monolithic. At all. To use your "How to educate my children?" example, some Christians believe it is morally wrong to do anything other than homeschool. Others believe it is morally wrong to do anything other than put your kids in Christian school. Others think that public school is best. Answers to such a question would become free-flowing debate, better suited for a discussion forum, not Q&A.
- Many "practical" questions require in-depth knowledge about one's personal situation. Such knowledge normally requires, at the very least, a conversation with someone else (such as a pastor). But here, all we get is text, and the tools we have for follow-up questions are limited. So we can't know your heart, and thus advice we give may not be on target.
- We aren't experts. Some of the "advice" I've seen given on this site is shockingly bad. A free-for-all of conflicting advice from different people with little training and different perspectives would, I suggest, be actively harmful to most questioners – not helpful.
At the end of the day, we don't allow these types of questions because they are too important. Most of the time, they are best addressed in the context of a local church, in which someone that the questioner trusts – a pastor, counselor, etc. – can view the entire situation and walk alongside the struggler.
That said, it is sometimes possible to frame "practical" questions in such a way as to get helpful, objective information here. For example, your example questions might be reframed as follows:
- Do Reformed theologians believe that true Christians can doubt their salvation?
- What is the biblical basis for homeschooling children?
- In Catholicism, is Christian fellowship among lay people seen as valuable?
These aren't the same questions, but the answers they receive might be of use. And they wouldn't devolve into a morass of debate, frustration, and conflicting advice, as we have often seen.
Further reading: Why can't I ask for personal advice?