The wallet is safe to use and uses same tech as Zcash wallet,if you just want to store coins for a year or two best option is a paper wallet storing your private keys offline,this is perhaps the safest method,there are plans getting BitcoinZ added to hardware wallet in future but until then using official wallet along with a PC protected with good antivirus software and stay away from porn sites and other dangerous sites with same PC you use for wallet is good advice,when possible storing your coins offline is safest method and paper wallet does this for you.
Private/Transparent addresses for storing coins makes little difference for security the important part is your private key which is something completely different,always backup your private key and store on something like USB hard drive like the 8 gig portable ones so if you need to restore wallet from new you can access your coins,wallet does not hold any coins they are stored on blockchain and wallet allows you to access them if you have private key.