Fees rise when there's a big transaction backlog. Since their price is dictated by a market, there's no reason to think that decreasing block rewards will affect them, because it won't change anything with blockspace supply/demand.

There's absolutely no difference what sort of hardware is required, mining is about converting electricity into hashpower.

There's no reason to think about changing the reward algorithm, we haven't yet seen what is going to happen when network rewards will become low. Maybe there's no reason to worry at all because the hashpower will remain sufficient to deter any potential attacks.