•What damages can a malware cause to your wallet?
•What are the signs that your wallet being attacked by malwares?
•How can it be prevented?
I think you're going at this all wrong. When it comes to malware, you should always assume the worst. Assume it's going to steal everything, and destroy all data on your computer. Once you've accepted that there is no safe online wallet, you can decide how to store your Bitcoins. So keep only small amounts on hot wallets for daily spending, and keep the majority of your coins safely offline.
"clipboard malwares"
See:
How to lose your Bitcoins with CTRL-C CTRL-V.
hmm this nice I. Know that hot wallet are easy to be target for hackers, keeping little asset there would actually be a smart move. So when it's comes to offline wallet which can you recommend for Me that would be more user-friendly. And easy to access.