[quote=@Obliviousdragon]
Oh, I forgot to ask. Where is it okay to just jump in and when is it necessary to first ask permission/submit a character?
[/quote]

99% of roleplays need a character/perm to join. But when the exception does happen, just below the title of a roleplay on a page there is Join Status.

If it says Jump-in, then... well, the name says it :)