Before i giving my POV, to the answer of OP
1) Yes, MEW is hackable, but likely impossible at the same. Regardless of what, private key is still a combination of characters, it just the matter of time people spent to find the EXACT same characters as your private key.
My take here:
It seems that that hacker "only steal KICKcoins and ETH" from the account, one of the hacked account/perhaps its owner account here
https://etherscan.io/address/0xe34c1d62e02c7cf5f729f439b5c7b77faa59a688#tokentxnsAs you can see this account has Everex which is worth $240
But only Kickcoins is withdrawn, The hacker Withdraw coins that doesn't even have a value currently.
So i suspect you clicked into some Hijacked Phishing Site. Once you upload your Priv key.
It auto access your account
Check Balance of ETH = True, Withdraw
Check Balance of KickICO = True, Withdraw
And based on what you have said, after transferring the hacked Kickcoin, they transfer it again to this address
https://etherscan.io/address/0xdee0cc222c5219ea79ca263beabdec5f9fc13dbc#tokentxnsBased on all these information, i strongly believe you clicked into one of the fake MEW Site.
Because if you actually take a look at this address:
https://etherscan.io/address/0xdee0cc222c5219ea79ca263beabdec5f9fc13dbc#tokentxnsThen check the tab "Tokens Transfer"
You can see each of the coins, are transferred by different Ethereum Account.
If you actually join slack, you would know recently it has tons of fake bots which spread fake message and tons of people getting phished.
However, this is all just speculations.
This address:
https://etherscan.io/address/0xdee0cc222c5219ea79ca263beabdec5f9fc13dbc#tokentxns could be someone else address, perhaps its an exchange or so. I doesn't have a good reverse tracking skills, but these is all what i can find
Just to check out, did you receive email, message or etc that stated your account is compromised, hijack or anything?