Wizzo

It applies for any visa, but is typically more often seen with immigrant ones (AFAIK). Who gets one is basically an unknown...some are random, some are believed to be based on country travel history or residency, etc.
 
You can request your passport back at any time. They cannot issue the visa without it, but once they complete AP, they will request the passport again to issue the visa.

My region is EU. This year for DV 2018 - is not good for EU visas because our quota is almost reached. Your region is OK. Still many visa numbers will be available in September. Just stay strong and wait. Keep sending inquiries.

If you think they might want to come after not too long, they can always land to activate their green cards then go back, but will need to be back in the US again within a year (or 2 years if they file for reentry permits, but that takes time)
cost of extra return ticket for now may not be so much vs cost of filing new petition (I’m not sure of cost but know it’s much more than dv)

Look up physical presence and continuous presence requirements for naturalization. basically you can technically keep your green card forever without ever managing to quite meet the naturalization requirements...but if you’re not actually living and working (or studying etc) in the us you’ll lose the green card too at some stage, it’s about intent not just the letter of the law. You can’t just touch base once a year and expect to keep your green card (same goes for your kids, they can’t for example keep their green cards by visiting you once a year in the US).
 
again, remember everyone has to enter before the expiry date on their visa. If your kids miss that and you have to go through the process of a LPR sponsoring children, it will be way more hassle, way more time and way more money.
 
a number of us have been through this already, it’s much harder in a way with DV with no job, spouse' family etc waiting like other immigrant visas, but at some point you have to take the decision whether or not to do it and then...just do it. 

5 years minimum to being a USC.  Or never.   My ex chose to wait 30 years .  My current had paperwork waiting to mail at 3 years ( as spouse of USC )  

Are your qualifications and experience related to the US, obviously laws, etc  are different here to many other places.
 
A friend of mines wife was the HR Director in the UK and now I think of it was asked to move to the US, she turned it down but obviously here UK based qualifications were not a hindrance.

Yup, don’t get too discouraged, it’s really difficult to get anyone interested until you’re actually on US soil. Even if you tell them you are or will be eligible to work, they’re always a little suspicious if you apply from outside the country! 
 
Your qualifications/experience are pretty portable geography wise so you have many options to choose what suits you as a place to live. The US is far from homogeneous, be sure to try do as much research as you can on as many factors as you can. Some people for example get attracted by a low cost of living somewhere to find they don’t like much else about the place, another example is people going places where jobs are plentiful and well paid but find that cost of living might still be too high, some people don’t care about politics and others find it really difficult living somewhere that the political environment is too conservative/liberal for them, some think they won’t mind the weather and then can’t bear the winter/summer...  I used citydata quite a lot in researching cities (also DV so also had totally open choice as to where to go) and found it very helpful.