1.「Onomatopoeic Adverb + Verb/Verb Phrase」
2.「Onomatopoeic Adverb + と + Verb/Verb Phrase」
The difference between the two in meaning and nuance is fairly subtle and minimal and both are equally correct.
When 「と」 is added, it can sound slightly more formal and for that reason, it tends to be more often used in writing than in speaking. The 「と」 places a small amount of emphasis on the onomatopoeic adverb as well. Please note, however, that these are merely tendencies and are, by no means, rules.
Also what's the difference the following two?
There is no difference in meaning -- none. Both sound pretty informal because of the 「ちゃってる」 endings. It just so happens that each entence omits one particle.
Needless to say, 「～～ちゃってる」 is the colloquial form of 「～～てしまっている」.
(For those of you who did not know, we have a ton of onomatopoeic adverbs that are in the physical form of
「Kana + small っ + kana + り」＝「〇っ〇り」.
How many of these you can freely and actively use would be directly related to how natural your Japanese is. We use a few of them on a daily basis.)
A good list can be found here: http://www.asahi-net.or.jp/~QM4H-IIM/k010502.htm