That looks like a cake of white tea. There are tools called tea picks that can be used to break the leaves apart or break chunks off, but you can also use a dull knife or anything that lets you wedge it in between the leaves. The goal is to break the leaves apart while leaving them as individually intact as possible.

For brewing, water temp does matter but Im not very familair with white tea, I would suggest doing a quick internet search, or you can experiment with different temps between 170°F-ish and boiling. I would recommend starting with a tea infuser basket, that would allow you to steep the loose leaves and remove them when done steeping. You could also look into brewing it gongfu style with a gaiwan or similar brewing vessel, again do a search for gongfu and you will find a plethora of information about tea brewing that way.

The tea subreddit is very beginner friendly, if you are ok with using reddit you can pop over there too, there is a ton of information about brewing guidelines and tea identification

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