sentences!

[Jenny Lau]

I cannot understand the following red words:
1.I grew up believing that Christmas was a time when strange and wonderful things happened, when wise and royal visitors came riding, when at midnight the barnyard animals talked to one another, and in the light of a fabulous star God came down to us as a little child.
Who are the wise and royal visitors? What do they ride on?Does it a custom in Christmas?
2.With my job as a meat wrapper and with a lot of ingenuity around the trailer, we managed to have elegance on a shoestring.
what does it mean by "with a lot of ingenuity around the trailer"?In the article, the family moved into a cozy trailer home in a forested area just outside of Redmond, Washington.
3.The day before Christmas was rainy and cold and gray. The three kids and I all but fell over one another as we elbowed our way about our little home putting finishing touches on Christmas secrets and preparing for family and friends who would be dropping by.

[Tdol]

when wise and royal visitors came riding= the three wise men who visited Jesus
with a lot of ingenuity around the trailer- the used their imaginations to make the trailer look good
but fell over one another as we elbowed our way about our little home putting finishing touches on Christmas secrets - there's little room in a mobile home, so they were nearly on top of each other as they added the last secret parts of Christmas (like not letting the others know what their presents would be)

[Jenny Lau]

Now, I see it refers to the three wise men, but"came riding" ? what do they ride, horses or anything else?
In the first sentence, why it says "God came down to us as a little child. " as far as I know, It is Jesus who came down to us, and Jesus is God's son, Is that right?
(I'm sorry, you know, as a Chinese, I don't know your religion very much)
What do you mean by "they were nearly on top of each other"? "on top of" here means"Following closely on"?
Thank you.

[Tdol]

Traditionally, they came on camels.
God has three parts- God, Jesus and the Holy Spirit, so Jesus is God in human form.
On top of = getting in each other's way

[Jenny Lau]

Thank u,tdol!!