Assuming your are doing this from a unix host, take a look at "ncftpget". Should allow you to do what you want without any need for a script (it supports all the options you mention). Just figure out your parameters and throw it in crontab.
You should be able to use wget or ncftp to transfer the files. As far as verifying them goes, I'm not sure... I would normally just use rsync, but I guess that's not an option here. Do you have ssh access to the remote server?