The fees to mint LLP, burn LLP or to perform swaps will vary based on whether the action improves the balance of assets or reduces it.
For example, if the index has a large percentage of FTM and a small percentage of USDC, actions which further increase the amount of FTM the index has will have a high fee while actions which reduces the amount of FTM the index has will have a low fee.
Token weights are adjusted to help hedge LLP holders based on the open positions of traders.
For example, if a lot of traders are long FTM, then FTM would have a higher token weight, if a lot of traders are short, then a higher token weight will be given to stablecoins.
If token prices are increasing, then the price of LLP will increase as well, even if a lot of traders have a long position on the platform. The portion reserved for long positions can be treated as stable in terms of its USD value since if prices increase the profits from that portion will be used to pay traders, and if prices decrease, the losses of traders will keep the USD value of the reserve portion the same.
If a lot of traders are short and larger weights are given to stablecoins, then LLP holders would have a synthetic exposure to the tokens being shorted,
e.g. if FTM is being shorted then the price of LLP will decrease if the price of FTM decreases,
if the price of FTM increases then the price of LLP will increase from the losses of the short positions.