Here is a list of associate members, https://ec.europa.eu/info/funding-tenders/opportunities/docs... which also lays out some of the terms.

If you scroll down there's a list of countries which can participate and who are automatically eligible to apply for funding too. So the EU, at least bits of it, despite all the talk of gardens and jungles, is still a force for good in the world.

Yes, but the deal is not really as a clean-slate external member just joined. Of course there are many pending issues from the past, as it would be expected, many long term investment and commitment were made and then one could colorfully say "the UK took the money and run" ( I know it's much more complicated than that ), and this deal kinda addresses that.

I'm not against this particular deal, in fact I'm moderately in favor. However IMO these kinds of 100 separate deals so the UK can get the "goods" while still being out are not good in the long run. ( the UK always had kind of a special deal since the 60s, but there is so much bad blood and misinformation it's pointless to acknowledge that )