I'm pretty sure my soil is a little too acidic from the organic compost I've used for it (Lots of fruits and urea). I've had tap water sitting out for about 5 days now. If I were too water the soil thoroughly with this distilled tap would it be beneficial and help neutralize my PH level? I don't have a PH nor do I have the money to buy a digital/disposable one but I'm also not looking for perfection, just a ballpark range. I'll also be planting my germinated tobacco seed in a few days, will a 42 watt CFL be too little or to much for a little baby sprout until it's older? I have about 200 more watts but I don't want to overkill her. +rep to good answers TY GC!
Distilled water is evaporated (boiled off) and condensed, leaving minerals behind and a final product of (relatively) pure H20, with a slightly acidic PH (maybe 6.9 due to CO2). By letting your tap sit out, you've allowed the chlorine and chloramine to evaporate, which is good for beneficial microorganisms and the plants, but it's not distilled. Using distilled water could serve as a "rough" way to manage your PH, since it is neutral. This is still not the optimal PH, though, and you should probably grab a meter asap. 42 watts for a seedling should be fine, though light is unnecessary until post germination.
Rain water should be similar in constitution to distilled water as well as have a similar PH, so yes. Tap water can range in PH a significant amount depending on your locale.