Preferred stocks are very different from shares of common stock most investors own. Holders of preferred stock are always the first to receive dividends, and in cases of bankruptcy, will be first to get paid. However, the stock price does not fluctuate the way common stock does, so some gains can be missed on companies with hypergrowth. Preferred shareholders also get no voting rights in company elections. They're a hybrid of common stock and bonds.
Dollar-cost average: This sounds complicated, but it’s not. Dollar-cost averaging means investing a set amount of money at regular intervals, such as once per week or month. That set amount buys more shares when the stock price goes down and fewer shares when it rises, but overall, it evens out the average price you pay. Some online brokerage firms let investors set up an automated investing schedule.
E (Very Weak) - The stock has significantly underperformed most other funds given the level of risk in its underlying investments, resulting in a very weak risk-adjusted performance. Thus, its investment strategy and/or management has done just the opposite of what was needed to maximize returns in the recent economic environment. While the risk-adjusted performance of any stock is subject to change, we believe this fund has proven to be a very bad investment in the recent past.
Regarding your private keys, can either keep them on a software wallet, or on a hardware wallet. The software wallet is the easiest way for beginners, but it implies that you have a computer that is properly secured (strong password, antivirus etc.) and that you do backups of your data. Remember, if you lose your private keys, the money is gone forever. As you get into cryptocurrencies more seriously, you will inevitably look for a hardware wallet, which is a dedicated device resistant to hacking where you can store your private keys (or to say it in an easy way, your crypto assets/invested money). I have already written an article on a hardware wallet, the TREZOR (see here). The most common wallets are the TREZOR and the Ledger Nano S. The TREZOR has a new model being sold from January 2018 (Model T) which will support much more currencies than the current TREZOR. The Ledger Nano S has more integrations currently, but I would recommend to wait for the TREZOR T to judge properly. Those devices usually cost around 100 USD, so once you have more than 100 USD to protect it starts making sense to get one.

Investor Protection: Along with wealthy and institutional investors, a very large number of small investors are also served by the stock market for their small amount of investments. These investors may have limited financial knowledge, and may not be fully aware of the pitfalls of investing in stocks and other listed instruments. The stock exchange must implement necessary measures to offer the necessary protection to such investors to shield them from financial loss and ensure customer trust.
Why I’m buying: Spell out what you find attractive about the company and the opportunity you see for the future. What are your expectations? What metrics matter most and what milestones will you use to judge the company’s progress? Catalog the potential pitfalls and mark which ones would be game-changers and which would be signs of a temporary setback.