Yeah, you can take the ALA with water as a dose at the time you need it and keep the rest of the powder from the capsule in foil or something waiting for the next doses.

The only thing about taking ALA with water, is sometimes you can get some burning in your throat from the 'acid", so that can be annoying, but just make sure you wash it down good.

Apart from that, dividing 100 mg up for times seems fine, but note that some people have to start even lower that 25 mg of ALA. Some have to go down to 12.5 mg or even 6 mg in some cases. So definitely just monitor how you feel and reduce if necessary or later increase as you feel you can. But before you increase, make sure you are able to tolerate the dose on a few rounds (like 4 or 5 rounds) before you make the decision to up the dose. Many have thought they could handle it and increased too early on and been hit badly on another round. Symptoms do not always show up on the first few rounds.