Immigrating to USA

#9 That sounds a reasonable way forward. Most of the other posts have been about immigration to the US for you but it is probably a lot easier for your boyfriend to immigrate to the UK, the major requirement will be that you need an income (circa £18K) to be allowed to sponsor him.

for most UK citizens, a B-2 visa is valid for multiple entry over 120 months. On each entry, you can be granted a maximum 180-day stay (not 6 calendar months). You can extend the stay, but there is a hefty fee and you must prove that you can still stay int he US without working or getting any salary or in-kind payments from a US source. (In-kind would include doing work in exchange for food & lodging.)

"I have a US citizen fiancée" would be a red flag for either a B2 or VWP entry, as that might be an indication that you will overstay.

An initial consultation with an immigration attorney, just to go over your options, might be a good idea.

If your children were born in the US, then they are probably US citizens. A US citizen who is over 21 can sponsor his/her parents to be admitted to the US as permanent residents. It's almost as much a hassle as spousal visas.

Is there any way I could extend the VWP 90 day visa or would I then be into the B-2 territory?

You cannot extend the 90 day VWP if you want longer then you need a B-2.

OK so all being well, maybe another scenario is have my boyfriend come here, I think my salary should I be successful in getting my temporary position made permanent, would be in the region of 17K to 18K, hopefully enough for me to sponsor him, then look at possibly going to USA at a later date.

#14 the current minimum income is £18600, more if he is bringing dependent children.

http://www.visajourney.com/content/guides

Look here and see what makes the most sense for you. A straightforward spousal visa doesn't really require the services of a lawyer.

Once you get married, you can apply for a Green Card (Permanent Resident) which takes a few months for the initial paperwork, and about $1200USD. Then you will have two years probation, but you will need to spend most that time in the USA, not in the UK, otherwise, they will want to know why you are not living in the USA as a resident if married to a US Citizen. The only away around the not traveling abroad too much on a Green Card is to apply for US Citizenship.

In order to get a Green Card, your husband must be able to prove he can support you. (IE: Job)

He also can apply for a Fiance Visa for you, but then entails interviews in the UK at the US Embassy.

Generally speaking, having a UK Passport is a much easier process usually, then holding a Passport from a developing country.

10 How long would my boyfriend get here without being on fiance visa?

With a US passport he will normally get 6 months in the UK.