#1
So, I accidentally ****ed up when trying to change one of the strings, and now I had to buy another set just to get the G string.
Now it's time to change strings again, and I have to use the set without the G string (which is 009), and the only fresh G string I have is from another set, which is 010.
Will the difference be much noticeable to have the G string thicker?

The bridge is locked btw, so no tremolo adjustment needed.
#2
No problem, you will feel some difference in playability though. But it is no technical issue. Be sure it is thinner than your D string and thicker than your B string.
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-Jackson Soloist Std. Professional '93
DiMarzio Evolution (bridge) SD Lil' Screamin Demon (neck)

-B.C. Rich Warlock Special Edition Metal Web

-Peavey Bandit 112
#4
There's minimal difference, I usually use a much thicker low E string on some of my guitars since I like to drop tune, so the tension matches. As long it's close enough it's fine.
Peavey 6505+ Head (Left)
Line 6 Spider IV HD150 Head (Right)
Marshall 1960A 4x12
ESP DV-8
Ibanez RG T42DX
Agile Hornet Pro 727