Don't worry, you're not going to hurt anything by clicking Skip. Thanks for doing your bit to help. It's appreciated.
Clicking Skip means "I can't decide, let someone else look at it". So if you weren't clear on whether those were okay, that was the right thing to do. The fact that the post was visible on the main page was not a consequence of you clicking Skip.
The second post you mention also was automatically put into the "Low Quality" queue and is also now in the "Close" queue, so it will be getting multiple sets of eyes pass over it.
A few comments on the "First Post" queue -- since people asking their first question or posting their first answer won't generally know how the system works their stuff is put into a review queue, so more experienced people like yourself will take a closer look. The idea is to look for a number of things like
does the question or answer meet the site standards (on topic, clear, etc*)?
if a question, is the title clear and relevant?
(will it help others with a similar question to find this post?)
is it appropriately tagged?
(not a complete list!)
* it's also a great place to spot the occasional spam posts
Depending on what you see you might comment to guide the poster**, or edit, or vote to close/flag for moderator attention, and so on
** (pointing out a relevant page of help, for example, or seeking clarification)
Once you finish taking all the actions you think are needed, click I'm Done. If it has no obvious problems, you click No Action Needed$^\dagger$, and as mentioned already, if you really don't know, click Skip and no harm done.
$^\dagger$ (even if it ends up out of the first post queue as a result, other people can still see the post on the normal "new" and "active" pages, so if you get this wrong once in a while it still doesn't matter very much.)
