.gycc cannot be decrypted, because it is a newer variant of the Djvu ransomware family. Newer ransomwares of the aforementioned family uses online ID, which is IMPOSSIBLE to decrypt according to Emsisoft’s decryptor. Your friend’s data is toast.

This.

A. You can fix this by CLEAN INSTALLING Windows. Your installation is toast. The clean install guide is written in the automated reply above.

B. Depends on whether or not you choose to fully wipe or keep your files. But it is strongly recommended to clean install instead.

Yes

This is probably due to bloatware (inferred by the slow boot time)