Tools to convert Unicode characters

Question

Which tool should I use to convert between various Unicode characters?

Examples:

1. Between various looks: Normal, Ｆｕｌｌｗｉｄｔｈ.
2. Between one-character and combining versions: ў (d1 9e) <-> ў (d1 83 cc 86)
3. From usual character to "subscript", "superscript" and "Combining" versions. Normal: i Sub: ᵢ Super:ⁱ Combining:_ ͥ

Just unicode tools helps, but it is not convenient to use for finding that characters.

P.S. normal to fullwidth onliner: perl -C63 -pe 's/(.)/((ord $1)<127 and (ord $1)>32) ? chr((ord $1)-0x20+0xFF00) : $1 /ge'