Well, I'm not a lawyer and certainly not an Argentine immigration lawyer, but I'll give you my opinions regarding your questions.
There are several different types of residency visas for Argentina. Which type you need depends on which one(s) you can qualify for. They are:
Rentista/Financier: you have to have at least U$S 1,000/mo of permanent income distributed to you due to ownership of some stocks, a trust, an annuity, or other business ownership that is not payment for continuing work done by you. You have to get a letter from a CPA stating these facts and one from your bank stating you are a customer in good standing, for how long, and with an avg. balance over the last 6 months of $XXX. And you have to open an Argentine bank account and transfer at least $1000/mo into that account for the duration of your stay.
Pensionado: if you receive retirement or disability payments from the USSSA (or British equivalent in your case) of at least U$S 1000/mo, you are eligible for this visa...basically. You must provide proof of payment from the issuing agency.
Then there's one for entrepreneurs, I don't recall the name. You must invest at least U$S 40k in a commercial entity in Argentina. This can be a farm, a shop, a taxi cab co., a factory, a professional service business, or virtually any traditional "business." It cannot be in the Argentine stock market or other purely financial investment vehicle. This one can be a bit tricky and is frought with investment risk.
Work visa: done just about like in the US.
Now, there are some things worth mentioning that apply to all of these visas. You must have no criminal record in at least the past 5 years. American citizens no longer require a health certificate, but as a British citizen you may. I'm not certain. All visa applications must be processed through the Argentine consulate in your COUNTRY OF ORIGIN. As a resident alien of the US, you MIGHT be able to process through an AR consulate in the US, but you will need documentation from the UK that you may not currently have in your possession. If you come to Argentina on a tourist visa and then want to apply for residency from down there, you will still have to apply via the appropriate consulate. That means your intake interviews, etc. must be done at that consulate. So you will have to leave Argentina to complete that process. There was an amnesty program running through the early part of 2005 which allowed folks in Argentina on expired tourist visas to apply for residency from down there. So some folks might tell you otherwise with regard to having to go through the home consulate, but that IS the law. The amnesty program has expired.
The consulate I've dealt with has been very helpful. I have friends who have also gone the "do-it-yourself" route and been fine just following the instructions from the consulate. That's how we are doing it even though our situation is a bit out of the ordinary. I'm certainly not paying an Argentine gestor U$S 5,000 to do it for us ($3000 for a single person was the quote from ARCA) when a) we can do it ourselves without any additional difficulty b) I already KNOW the gestor gave me bad legal advice.
The best advice I can give you is to call the appropriate Argentine consulate in your region of the US and tell them what you want to do. They'll help you and they are (in my opinion) much more likely to tell you the truth. It seems like every attorney and businessperson I've dealt with in Argentina has an "angle" they're working. You will find that many other foreigners who have dealt with Argentina will tell you the same thing. ARCA isn't the first law firm in BA that has brazenly misrepresented Argentine law to me with regard to immigration, taxation, real estate law, and more. However, they are usually quite willing to start their hustle BEFORE you actually pay them any money, so they're not too difficult to sniff out. Of course, I am a professional investigator.
Hope this helps.
