About antiviruses.... erm... of course that one time where Apple and Google had a break in of a malware was indeed worrying... but in general, it's not the case. It's still very safe to buy/download apps from these 2 stores.

Make a backup. Antiviruses in the meantime are not necessary.

That's in my opinion la~

is there an app like ccleaner for andriod? or any app that will clear registry or like driver sweeper? cus i uninstall a few stuff but their folders still there. although some are empty or have minimal files but i dont like to see them there lol.