Very much depends on the price of these tokens. Perhaps this token cannot be sold or it costs very little, so the number of tokens does not matter, much more important is the price of them
I think first of all it depends on the value of the project, if your bounty is a potential project, I think no need to pay attention to whether the bounty pool has more or less tokens.
More or less it's just a tiny percentage of the actual ico sales, so even they gave the bounty rewards if the project is really successful and have a goal for future development, that portions of possible dumped after the rewards won't affect too much, its all about how well the developers will build the success of their projects, tokens are calculated accordingly if the team is well organized.
Not necessarily, some bounty will fixed bounty bonuses, regardless of sales in the ICO. And one more thing is that the bounty hunters will sell their reward and cause the price of the currency to go down, but the investor really feel disappointed and lose confidence in the project.