Yes, the portfolio cost minimization is not currently included in the main objective. Because of this it can produce a wide variety of portfolios for the same amount of the income. This allows one to explore a wider solution space and then gradually tune the portfolio as needed. I have it in my todo list to add a minimization as an additional objective and will start working on it shortly.

Issuer is basically just one record in a portfolio, like one company or ETF, potentially with multiple shares. This allows you to express conditions like - "I don't want more than 30 entries/issuers in my portfolio", or "it should consist of at least 20 ones" and stuff like that.