read the comments from an ex-border force officer, scan passport coming in, not going out, if you're not a wanted criminal, or of any interest to the authorities, it seems nobody takes any notice.
yes it's a £40 annual once a year payment, everything is manageable with your 1p mobile online account, my phone is duel Sim, both UK and thai Sim cards are always active, when you dial the number as previously explained, choose to make the call from your Thai SIM, it seems with AIS you dial "003" to make calls, dial as previously explained, whenever possible make the call with your Thai SIM, try only to use the UK SIM to receive free messages, for banking purposes etc etc, only use the UK SIM when absolutely necessary, because the last time I made a call to a UK landline from Thailand, it was £1 a minute with UK sim, do a Google search "cheap international calls with AIS" can help you to understand better.
Order a 1p mobile SIM card online, get it sent to a relatives address in the UK, get them to activate it, and send it in the post to Thailand, it's now £40 for one year, it's free to receive text messages in Thailand, what network are you using in Thailand?? I use the true network, if you dial "006" first, and then miss out the + add the "44" miss out the first "0" of the number your calling to the UK, it's very cheap, I've done it myself many times.
sorry I'm not sure about the new DTV, but it's a multiple entry visa, so I can't see why not, providing the country you bounce at, allows to leave the same day, but when I previously had an METV, doing border bounces with Lao, was very easy at the land borders, going from Mukdahan or nong khai, I just walked around in a circle and back into Thailand the sme day.
I suppose it depends which route your going to go down, do you want to do it yourself?? Or are you going to use an agent?? If you want to do it yourself, and you have everything in place, money in the bank etc etc, I believe it's a very simple process, to apply for the initial non O, based on marriage or retirement, through the Thai e-visa website in your home country, before you come to Thailand, if you want to do the initial non O in the country yourself, some immigration offices, will make it very difficult or impossible to do it yourself, and they will suggest you apply at the thai consulate in Vientiane Lao, and then after 60 days, return to them for the 12 months extension based on marriage or retirement, if you decide to use an agent it is very easy, if your entitled you can just arrive on a 60 day visa exempt, and extend that for 30 days, that gives the agent enough time to complete the whole process, everything will be done for you. I'm no expert, that's to the best of my knowledge, if anything is wrong hopefully someone will correct me.