Yes, Hong Kong is connected to China by land through undersea tunnels and bridge.
Yes. HKSAR or the Peoples Republic of China allows you to bring your dependence on a recognized same-sex civil union or an opposite-sex civil union if the union is lawfully recognized by [...]
The department that deals with Hong Kong Long-Term Visa related issues is the Immigration Department or the Chinese Diplomatic and Consular Mission. You may be in touch with them through the post [...]
No. You can utilize the authorized maximum three-month period.