So if I, by some miracle, were able to get a work visa, you mentioned issues with limits on who qualifies for permanent residence and citizenship. By that, were you referring to more than the salary requirements and 5 year timeframe you mentioned?
Well, the 5-year timeframe has always been there (5 years to permanent residence, 6 years in total to UK citizenship), but now they've restricted it so that anyone applying for ILR based on a Tier 2 work visa from April 6th 2016 will need to be earning at least £35,000 per year (
http://www.ukba.homeoffice.gov.uk/visas-immigration/working/tier2/general/settlement/).
I could financially do a student visa if I absolutely needed to - but I'm not sure I would be able to sustain paying for all of the tuition out of pocket without benefit of student loans after the first year or two.
You don't have to pay for it all out of pocket if you don't want to or don't have the money.
The majority of student visa holders here on UK-Y use US student or private loans to fund their studies.
And from what I've read, I can work on a student visa, but only for a max of 20 hours per week.
Yes, that is true, although in order to get the visa in the first place, you must show you have access to all the money for the first year of study and living costs without needing to work.
However, if I was there on a student visa, I could switch to an unmarried partner visa after 2 years (or spousal visa at any time if we married).....did I understand that correctly?
Yes, as long as the rules haven't changed by then. However, the 5-year count to getting permanent residence (ILR) won't start until you get your unmarried partner or spousal visa, so say you moved on a student visa in 2013, then lived together until 2015 and applied for an unmarried partner visa then, you wouldn't qualify for ILR or citizenship until 2020.
Alternatively, say you married now and moved before the end of this year, you could qualify for ILR and citizenship in 2017.
However, as that is one of the potential options, is there anything we should be aware if we do end up going that route? He would need to make £18,600 - is that for a certain length of time prior to the application? Any other requirements or things that would be helpful to do now if we end up going that route (ie, documentation, etc.)?
The rules have just changed for spousal and unmarried partner visas - the main changes being that your UK partner needs to earn at least £18,600 per year (if you are applying from the US, then your income does not count at all, if you apply in the UK after already living here, your income will count) and you can no longer use third party financial support (i.e. from a family member) to meet the requirements.
Also, the time to ILR has increased from 2 years to 5 years (you now have to get two 30-month spousal visas instead of one 2-year spousal visa), so you can't qualify for citizenship until you have spent 5 years on the spousal visas and have ILR (used to be 2 years to ILR and 3 years to citizenship, now it's 5 years to both).
Here's more information on the requirements:
http://www.ukba.homeoffice.gov.uk/visas-immigration/partners-families/citizens-settled/spouse-cp/