I think your open options are all not really suitable. Where is the point in doing a MRes or MPhil if you already hold a Master Degree? If you plan to settle in 2-3 years a PhD is also no option. I think in the ideal case you can maybe finish in 3 years but there are only a few students who do so. Most take rather 4 years.
Why don't you just find a job now? I don't think that a PhD is so beneficial for an engineer ...career-vise
For the last part: Just apply for funded PhD positions that are available for internationals. If you get a position, they will tell you how the procedure at the university works. I don't see any other options. Personally, I would never do a non-funded PhD or something part-time that I have to fund by working and I think that is also not an option for you, as part-time would take you up to 8 years