In the books, is there any information on what type of letters the Hobbits used when writing or printing? The Elvish scripts, runes, or something else? Thanks!
From Appendix E, "Writing and Spelling," section II, "Writing" of The Lord of the Rings:
The scripts and letters used in the Third Age were all ultimately of Eldarin origin, and already at that time of great antiquity. They had reached the stage of full alphabetic development, but older modes in which only the consonants were denoted by full letters were still in use.
The alphabets were of two main, and in origin independent kinds: the Tengwar or Tîw, here translated as 'letters'; and the Certar or Cirth, translated as 'runes'. The Tengwar were devised for writing with brush or pen, and the squared forms of inscriptions were in their case derivative from the written forms. The Certar were devised and mostly used only for scratched or incised inscriptions.
The Tengwar were the more ancient; for they had been developed by the Noldor, the kindred of the Eldar most skilled in such matters, long before their exile. The oldest Eldarin letters, the Tengwar of Rúmil, were not used in Middle-earth. The later letters, the Tengwar of Fëanor, were largely a new invention, though they owed something to the letters of Rúmil. They were brought to Middle-earth by the exiled Noldor, and so became known to the Edain and Númenoreans. In the Third Age their use had spread over much the same area as that in which the Common Speech was known.
So Westron (as Common Speech is properly named) was written in a variant of Tengwar, the "Tengwar of Fëanor."