I am curious to know if it is possible to easily buy $5 of Bitcoin and sell it a few minutes later, trying to make mini profits for fun, or are the waiting times etc... Too long?
It will take a while to get money to an exchange platform, but once you have an account and a balance there, trading is very quick. A lot of people try to do exactly that: They buy low and sell at a profit, or buy on one exchange and sell on another for a higher price.
However, trading on exchange platforms happens off the blockchain, i.e. all the "score keeping" is done by a company in their bookkeeping. It would not be as easy to trade bitcoins by actually holding them, then you would be impeded by waiting for confirmations on the transactions which in average take about ten minutes. You could still trade on large swings over a few months that way, but mini-profits would be very hard to time with such delays.