There is his website as mentioned before (logan-lerman.com). But, the site has been seven years in hiatus, so it might have changed. Currently, there is no exact place you could send it to, without being positive about it. (Just to note, he does not have a twitter, facebook or a myspace.)
I don't have the address with me but on logan-lerman.com that had a place where they had his reliable fanmail. and in the back of most Tiger Beats they have a list of stars fan mails where you can send packages and letters and such.
yeah totally.
go to logan-lerman.com then go to information and scroll down and you'll see CONTACT LOGAN click on it and then u will see. from what i hear its accurate.