Use the TAB key to read all unread articles in all subscribed to newsgroups. The messages are printed in the syslog file because your nntp server does not support some of tin's nntp extensions. The 'H' command at any level will toggle the mini-menu on and off. The -c command forces tin to mark saved articles as read in the newsrc. Therefore create another newsrc file that contains just the groups that you really want to save for later.
T is the number of threads in the group.
A is the number of articles in the group. K is the number of killed in the group. R means that only unread articles will be displayed. There is an 'Introduction to tin' document written by Paul Kramer that is included with v1.3 PL0 onwards. Both OS's seem to have pretty screwy terminal drivers that not setting the terminal to raw mode.