'Does sound proofing and insulation help with condensation on the windows' ?
No, keeping the temperature inside the van high enough that the relative humidity stays below 100% helps with avoiding condensation. You could have no insulation but so long as you keep the air warm enough, it won't release its moisture.
Stopping the warm, moist air meeting a cold surface is the best way to avoid condensation.
Insulation will help (as will insulating the windows as they tend to be the hardest part to insulate, ie you can't stick insulation to the windows) but it's a hard won fight.
Any drop in temperature with high humidity means that the amount of water a given volume of air can contain reduces, so it drops out (dewpoint)
Keeping the van just warm enough and getting a through flow of cool, dry air in on one side and letting the warm, moist air out on the other side helps a lot.
Keeping the relative humidity below the 100% line on the psychometric chart is the way to do it.