Hello everybody! Glad to join the team!

I'm a freshman to use the Wikidata, and face some confusions:
1. I though Wikidata gathered data from Wikipedia infobox, but I also find that, the statements and infobox are not entirely corresponded. Some infobox data are missed in statements and the Statements also have more data than infobox. Then how does Wikidata actually create a new item? What's the detailed process? If there are new or updated articles in Wikipedia, how does Wikidata catch these updates?
2. I think there are more valuable information in Wikipedia but not included in Wikidata, e.g. categories, infobox data. How can I enrich the Wikidata? I know I may use & follow WikiData Bot's process, any directions?

Any suggestions or guidance are welcome!

BRs,
Sherlock