i want to know information about tags

Unfortunately, there is not an easy answer as tagging guidelines vary from country to country, especially for roads. I would start at the Tagging wiki page, and see if your country has a link under Recommended Tagging Scheme By Country. You could also look at the Highway:International_equivalence wiki page--even if your country is not listed, you might get an idea of how to tag from how a similar country does it. You also could look at how other mappers in your area have tagged roads, and even send them a message via OSM to ask advice. You can see who has mapped an object by looking at the history of an object. Find mappers in your area generally via the Who's Around Me? map.

I have a hard time understanding what you mean exactly. Could you refrase to make sure we understand correctly?

Usually all roads within a village are tagged as highway=residential. the major exception would be if a road connecting the village to other places goes through the village. If that road is highway=secondary , in most cases it should stay secondary within the village. In larger villages or towns, you might tag roads as tertiary or higher up if they are much more important. For example if the collect the traffic going from one neighborhood to the next.

About the red dots in your drawing. In Openstreetmap, a road is a line made of nodes (or points). The last node is shared with the road it joins. In iD or JOSM, when you draw a road, this is done automatically if you end your road by clicking on the other road at the place where they should join. You do not need to create any special tags in order for this to work.