Doncaster have made forward Dany N'Guessan their sixth summer signing.
Shrewsbury have rejected an offer from Burnley for winger Josh Ginnelly.
Kelly, 19, has been a regular member of the U20 squad and has featured on the bench for the first team on a number of occasions, although he has yet to make his senior debut.
He made 10 appearances for East Stirling during a loan spell in the first half of last season.
Naismith, 18, whose deal will keep him at the club until at least the summer of 2014, has made two substitute appearances in the Clydesdale Bank Premier League.
He was loaned out to Morton and Cowdenbeath last season and played 11 matches.