3)Use of advertising revenue
This the only place I know that forces a person who buys a TV to get a BBC(only) license.
Do some research
There are loads of countries with a TV licence style system - many don't give you any opt out at all (IE you own a TV you pay it refardless, or it's lumped onto your electricity/bb/phone bils), and some charge you a TV licence but it goes straight into the governments coffers with no service provided.
There are also countries that require you to pay a licence per car radio as well...
My choice would be either leave it as it is, or add it to the council tax and ring fence it.
If you go subscription it cannot stay a PSB and would have to go for maximum cost effectiveness content - so no more niche titles, no more taking risks on new (but expensive to start up with) titles, no more documentaries that might take years to complete (Discovery is reportedly about to drop it's collaboration with the BBC for documentaries as it sees the History style "reality" stuff as being more cost effective).
You also run into the problem of a massive cost increase in administering the system, and the subscription cards (it would cost a not inconsiderable sum) - the current system has the advantage that it's pretty cheap to run, and doesn't cost any more for you if you have one set, or 4 sets and 2 PVR's.
If it goes advertising you end up with an immediate drop in content per hour of around 20-25%, you can no longer have shows that are critical of products as your advertisers don't like having their new car/computer/phone etc being slated for being rubbish.
You also run into many of the problems associated with subscription funded TV - why bother paying for a show that only gets half a million viewers (but is high quality, thought provoking and educational), when you can get a show that gets 5-10 million viewers but is absolute dross with no long term value, ut it costs less...(one of the reasons ITV was in trouble for a whilst was it went down the route of "reality" and "celebrity freakshow" TV at the expense of anything scripted).
Not to mention the advertising pot is dropping in size, already highly diluted and it would likely kill off a lot of the current commercial channels who simply would not be able to compete with an ad funded BBC.