Ok. Now almost all doubts are cleared.
One last question(silly) if I want to mine litecoins in pool, which is the best pool and what mining softwares are best for litecoin mining?
Also, is there any secure online wallet for litecoins?
I just installed the litecoin Qt wallet but it would take a lot of time to download the blockchains.
I know some like blockchaininfo and coinbase for bitcoins, but I haven't heard any secure online wallet for litecoins.

Also, what should I do with the BTC & LTC address that I get when I install Qt client? Are they totally wasted?

Thanks for helping me out!!