Hi, Yadirf,
You asked,"Why is it ONLY the missionaries...that go to people's homes to spread the Mormon beliefs (referring to the 2-year full time missionaries)?"
Answer is: It isn't. We all are responsible for missionary work. We all have the opportunity to do door to door work in our communities, if we desire to do so. My family does. However, there is a time and a season for all things. The full time missionaries, who put in approximately 10,000 hours of door to door work in their two years, knock on thousands of doors during that time. That is what they are called to do. They also teach classes, lead meetings, lead music, etc. Whatever they are asked to do.
The rest of us (and them also, both before and after their missions), have other responsibilities, in addition to every member being a missionary. The Bible outlines other duties of members, such as to strengthen one another, to teach, to visit those in need, to meet together often (inferring a need to have someone lead those meetings, set up for those meetings, etc.). If you cannot find such lists of duties of members in your scriptures, I'll supply a verse or two.
Most of us have multiple callings that, IF we were to keep time (which we don't) would easily double what most people would consider acceptable religious duty. We teach in classrooms (ages 18 months through adult, children, teens, men, women, Elders, High Priests) divided by many different classifications and each requiring a fully-prepared teacher. Every Ward has about 20 people called to teach, some teaching EVERY day, a calling I have thankfully never been asked to accept.
We have people called to lead the young people in scouting, in activities, in various youth programs that keep our young people active and involved, and help keep them away from the harmful things of the world. We have people who do social service duties, helping those in financial, emtional, legal, or spiritual distress. We have those called to minister specifically to those in prison. Others called to help those physically in need. The list goes on and on. We consider it our responsibility to help in every possible way anyone in need, whether in our own congregation, or our neighborhood, or our community, etc.
Most of us do in-home visiting and teaching of several families on a regular basis, and as part of that, are "on-call" for any needs those families may have, 24 hours a day, 7 days a week, from help shoveling snow or providing rides to doctor visits, to taking care of their children, pets, farm animals, etc., when they need to be out of town (let me tell you, THAT is one huge responsibility). We truly believe in being our brother's keeper. And we don't just give that lip service or empty platitudes. Love is an action word, for us.
Door to door work is important, but not more important than helping those who are already members, or others who are not members, and may never be, but are in need of our help. Door to door work is one facet of Christian service. You ask why we don't all do it, as JWs do. I wonder why your religion puts so little emphasis on blessing the lives of others through ongoing, genuine, meaningful acts of service and through other callings that provide opportunities for service.
I have often heard JW family members bemoan their problems with finding assistance with some problem they are having, such as not being able to find someone to provide transportation when their car breaks down, not even having anyone they can phone to come pick them up from the garage, and I wonder why not? Why isn't there someone there for them? What good does it do to do X number of door-to-door hours and then be unavailable when someone in your own congregation has a need? That makes no sense to me, and it never will.
Showing "love" to strangers is great, but is hollow at best if "love" isn't shown in more practical ways to members of your own congregation family, and your own neighbors and family members, whether members of your congregation or not.
You also asked, "To what degree is it acurate (Mormon doctrine) ... that God makes his home out on some planet in the univers...has wives...produces children...spiritual persons...sent earthward." And also, "Is God a spirit person or a physical person."
Yes, God has a home. Exactly where it would be if you went out and pointed at the night sky, none can say. Does it matter? Yes, he has a wife, whom he adores and cherishes in the same way he expects us to adore and cherish our own spouses, only far, far better since everything he does is far, far better than we can do. Notice I said "a wife". They have children, who of course are spirit beings, with spirit bodies that look much as ours do. The spirit part of us never ceases to be. He is spirit, encased in resurrected, glorified form. We are spirit, encased in mortal form. Mortal is temporary.
Does that cover it?
Susan