How to keep Podcasts as Saved on iPod

I have OS 10.6.8, iTunes version 11.4 and an iPod Classic (160GB).

I have two questions :

(a) I want to be able to keep Podcasts permanently on the iPod (or until I decide I no longer want them). I click the arrow (white, in a grey circle) to the right of the name of each Podcast and select 'Save Episode' so that that phrase changes to 'Remove from Saved Episodes'. This I assume is to give me the option to 'remove' as and when I want to remove them.However, when I connect my iPod again, I find that the previously saved episodes have reverted to the unsaved state. I've lost track of the exact history of all of this (I have, at present, 452 Podcasts on my iPod) but I distinctly remember finding some missing at some point and having to copy them from iTunes again.

So, my first question is : How can I ensure that when I save episodes on my iPod, they stay in the saved state?

(b) What exactly does the small tick mean, just to the left of the name of the episode/music track?

Again, I find that some of these seem to get unticked.