I'll try to explain everything as simple as possible.
1. You can download the wallet .exe file from the offical github link, just look under the assets tab on the front page over here.
2. The atomic/light wallet is yet to be fully released.
You can either stake trough the Cloud or the regular wallet. If you have a few hundred XSN, you can use the Cloud to receive some staking rewards that otherwise can take months for you to earn with the regular wallet. Keep in mind there are risks associated with the Cloud as it is a centralized solution.
3. The cloud wallet is a centralized staking pool, you stake by yourself when using the regular wallet hence the odds of recving any blocks(staking rewards) will be minimal unless you run a masternode. You don't necessarily need a cloud wallet to run a masternode , you can however host your masternode trough the cloud using the MNaaS service, you'll still remain in control of your funds in your own regular wallet but the cloud will automaticaly update the VPS and provide maintenance for a small fee. Have a look at this article for more in-depth information about the different staking options: https://medium.com/stakenet/trustless-p ... 7245eb9640
4. If you have 15K xsn you should definitely run a masternode, have a look at this video guide of how to host your masternode trough the cloud using MNaaS. https://www.youtube.com/watch?v=x9_YdU8vWrU
If you have under 15K you should consider TpoS or just simple staking trough the cloud wallet.
5. Have a look at the Stakenet medium page, you'll find a bunch of helpful articles + the weekly dev updates. https://medium.com/stakenet
I also recommend you checking out our Discord or Telegram channels, the community is much more active over there!
Feel free to ask me if you have any futher questions and welcome to the community