Two question! First one is Simple. To understand how a coin works, you need to Google search and know youself from article related to that coin or go to that coin's telegram account and ask there what you want to know. Admin and others member will guide you and give you info. Coin price is low during token sale. If they late, fail to give you satisfactory answer or you find something phishy then avoid the project. But it hard to know which project will success.
in my opinion, Consider the market capitalization and trading volume of the altcoin. Higher liquidity makes it easier to buy and sell, and a substantial market cap might indicate a more established project.