We're probably talking a bit over the OP's head.. The main reason people are suggesting higher voltage (or variable voltage like the eGo twist which can go pretty high) is higher voltage gives more and hotter vapor generally. It also gives more "throat hit", which is important for some people to simulate smoking. Your husband is likely to take to vaping much easier with less withdrawl problems using a higher voltage device than the little cigarette sized ones. mAh determines how long the battery will last before it needs to be recharged, obviously the higher mAh the bigger the battery/overall device is. With things like eGos they keep the same diameter (for the most part, there are a few exceptions) but get longer. Other than my very expensive Zenesis rebuildable (which is not a starter PV by any means) I'm using an eGo 1100 mAh with 12mg nicotine juice (I stepped down from 18mg, I was about a pack a day smoker 3 months ago). The battery goes quite a long time before it needs to be charged. If you were to go with this setup you husband would probably need about 24mg nic juice, and your son 18mg. But it would be better overall to get a twist for them if you go with an eGo so they can get the higher voltage if they need it.
Whatever you go with make sure each man has at least 2 batteries and a car charger if they only have access to their vehicles and/or wall charger adapters if the devices come with usb chargers. Most kits will come with all this except the car charger. I've seen car lighter to usb adapters at several local gas stations which would work if you can't get them with the PVs. Nothing will force a smoker back to the stinkies faster than running out of batteries at work. If they will have no way of charging a battery at work in a pinch get them 3 batteries each, it's an extra expense but worthwhile.. and if they end up not needing them or switching to a different device eventually you can sell them on the classifieds here and get back a good portion of the money.
As far a withdrawls and transitioning.. a lot of people take to it right away, some people have problems. There are other alkaloids in cigarettes other than just nicotine. Most e-juice only has the nicotine. There are special types of juices that contain the other alkaloids. So have them try with the regular juice first, if they're have a really hard time come back and poke us for more information about those special juices to ease the transition. Also - don't beat them up, and don't let them beat themselves up if they don't do a 100% transition right away. Every stinky avoided is a triumph.
