Does wikipedia delete new/bad pages right away?

Like, a certain page that's just been posted... do they look at ALL of them before posting them, or is the page posted right away and deleted later if they find it?

Not exactly "instantly", but very quickly. People constantly watch the "new pages" list. Whenever a new page appears, they check to see what it contains. If it is just a garbage page, they tag it with {{{db-nonsense}}} or {{{db-test}}} to signify that it should be deleted, since it is of no use. If it insults somebody, they can tag it with {{{db-attack}}}. An administrator will look for these tags, see the page, and decide if it should be deleted or not. Most "bad" pages will probably be deleted within about 10 minutes.

I don't think wiki deletes them, I think other uses come delete them or edit them. Maybe if it was a very new topic they may look at it first, it makes sense...

The pages are immediately posted to the website, but the administrators of the website do obtain a list of the "recently updated" articles, and view them. Random people can also delete pages.

If Wikipedia deleted bad pages, it wouldn't exist. All of Wikipedia pages are bad!

Only if it is found right away and found to be incorrect.

If it is never found it is never deleted

There is something called the new page patrol, where people check look at as many new pages as possible. If the edits are good, and if the article looks good, it will stay. If it's useless, or if the article is just plain silly, the article would be requested to be deleted. If the article was really bad, then it would be deleted within a few minutes. Not all new pages are bad though.
Now, the only person who creates the article can look at it. Nobody can see the article unless if it is posted. When you post it, you post it.

The moderators put a template warning you that the article will be deleted in 14 days and if you don't change it to meet wikipedia requirements. You can go to the talk page of the article to explain why you don't want it to be deleted.