The summary page aggregates and displays the stocks from the Portfolio. However, if for some stocks the cost price is not entered, they are not aggregated.
You need to edit such stocks and enter the cost price. Once done, the Summary page should show the correct quantities.
A basket or a cart is a way of collecting shares which you want to sell.
You collect stocks into a basket (or cart) and mark them as sold.
For the similar reason to #1, stocks need to be updated properly before it can be added to basket.
WACC (or weighted average cost of capital) is the average cost of the share. Sometimes, it is also called as Effective rate.
It is a calculation of investments in which investments are proportionately weighted.