Can Creating bookmark in TBB add any security risk for user? Can anybody read any of these bookmarks remotely?
Your bookmarks cannot be read remotely (but see below). However, anyone that gains physical access to your computer can read them, of course.
The above statement about cannot be read remotely is not entirely correct. As mentioned here (as pointed out by Jens Kubieziel), if your bookmark is not an trivial URL (like https://duckduckgo.com), it may contain a unique identifier that enables the server you connect to to know you are the same one from before.
A non-trivial URL may look like https://www.google.com/imghp?hl=en&tab=wi&ei=AtjnUrO_MuXjywPXy4IQ&ved=0CAQQqi4oAg. You don't know if that extra stuff is a unique number for you (it probably is). Even just a simple number after the / may be unique to you.