Blender 2.8 - Rig Proxy, layer mask?

Hi artists…

Does any one know how a character fully rigged in 2.79 will be linked in 2.8 as proxy?
is there any way out?

Similarly, kindly share me the technique to be used in 2.8 similar to layer mask in 2.79
(if there are many collections in 2.8 and i want to use a particular collection to mask other collections, what should i do?)

If there are some tutorials available in youtube etc, kindly share the link