Yes, it's a flat fee, it only increases if you want extra coverages (full pay on day 1 of sick leave, unenmployment, etc).
The mandatory minimum doesn't increase which income†, but since you are also paying towards your retirement, you can choose to pay more, if for example you are in your final working years, so that you get a better retirement. But I'm not thinking about that right now :)
I am not the right person to ask about these things, and I may be wrong, but I think the workaround you are suggesting would cost, in the best case, the same as being autónomo on your own. You'd be paying about 250 € in taxes for a worker with the minimum wage (758 € in 12 wages).
†: of course you will have to pay income tax later (annually if >=70% of your income is B2B, quarterly if not, so many random rules!).
Yes, with that money you pay social security and health care, which is fully covered with the minimum, mandatory "autónomo" fee. That's nice I guess.
Unemployment is optional (about +20€/month IIRC), to get it you have to prove a specific lost of revenue in a specific length of time, first year doesn't count, and you get 2 months of pay per 12 months worked ("normal" jobs get 4/12). I recently read that only about 25% of the unemployment petitions are approved. I chose not to pay it.
Since the moment you stop being an "autónomo" you get 90 days of "free" health insurance. After that, if you are <=26, you can use the health insurance of a parent or sibling. If you are 27, you have to pay for health care, or prove that you don't have any income to get free healthcare.
If you want to be a "trabajador autónomo" (autonomous worker), you have to pay a mandatory monthly fee of about 250€ (it varies a bit on your activity, if you want extra coverage, etc). There are some discounts, if you are under 30 (35 if you're a woman) and it's your first time being an "autónomo", you pay only 20% of the tax on the first 6 months and 50% on the next 18.
The 20% thing was approved about a month ago, and it's been a bureaucratic mess. I applied to it on the first day of being on the law, and as of today I'm still waiting for approval. Apparently their systems are not prepared for this discount and they have to be applied manually. Of course you don't have to wait, you can pay full rate and then claim the difference, but that could take months.
If you create a SL, you must designate a legal administrator, and the cheapest way is being an "autónomo".
Edit: about creating a Ltd in the UK, if your revenues are more than 50% from Spain, you will be fined by the Spanish IRS for capital flight. It's not easy.
When the Last.FM leak surfaced, I e-mailed all my non-technical friends who used it, warning them and explaining why and how they should change their passwords. Sadly, my message was received with a general tone of "you computer nerds, always complaining", and promptly ignored.
While it's true you can find decent tablets for 100€, most of them have a problem which has been a deal-breaker for me: the aspect ratio is always wrong. In portrait, circles are squished horizontally; in landscape, circles are squished vertically.
I can't understand how that can happen and the manufacturer doesn't seem to notice or care.
Enabling click-to-play in Chrome (and not one of those extensions that hide or remove from the DOM the element once it's loaded) just makes the fingerprint to have less bits, since it can't get the list of the installed fonts on your computer.