It can also be written as "〇", which is what you'll usually see in things like years.

零 more quite literally means "nothing" than it does "zero."

零 I remember this by thinking "It's raining over the house"

Yep, it's written differently and more complicated.

It does doesn't it

It look like Baltoy meditating Pokemon

Actually, the character "零" IS related to rain.

Originally, "零" means "drops of rain/drizzle" in old Chinese. Later this character was used as the verb "to fall down like rain". You can still see this usage in modern Chinese, albeit not very common and too flowery in conversation:

"凋零": "scatter about"

"涕零": "tears falling down"

Another derived meaning of this character is "tiny bits". as in "零钱" (change, dibs). Which is probably related with the modern usage "zero". However, it's more likely that "零" just had the same pronunciation as "zero" and thus people borrowed this character to write "zero".

Really not that many