The battery in the first Amazon link has a clue in the title. It is intended to power a Futaba transmitter, meaning low current delivery for a long time. It will not drive a fast boat without damaging itself.

Like Dave says, look at specialist model trade suppliers, they are likely to carry what you need, rather than what the Amazon and Ebay box shifters would like to shift. Very often, the prices compare well.

More volts makes the motor spin faster, but draws more current and heats things up more up to the point where the magic smoke comes out. For a given capacity, the increased current means a shorter run time. Increasing capacity gives a longer run time but usually means a heavier battery for any particular technology. Lithium batteries tend to be lighter for any given energy stored, and are usually capable of letting it out faster (ie much higher current out) but as a result need more care in handling. Like all other batteries, this means having an appropriate charger, but also means having a low volt alarm in the boat since the easiest way to kill a Lithium battery is to over discharge it.