[General Questions and Answers] codQuore:
1. The stock browser I believe does get updated when the OS is updated. I've read about people getting OS updates to find the stock browser is then faultering and assume this then gets updated. The update of the OS is usually done by the device manufacturer unless you are using a custom rom. Whomever creates the rom used on the device, is responsible for the internal updates for it, to whatever level they wish to support it. I have read that google don't mainstream care about the stock browser as they are pushing Chrome for the win and a separate team deals with the stock browser.

2. The world and his hedgehog are not safe from hack exploits. The quality of protection out there in any sense is mirrored by the quality of hacker. If you have a crap security level, any old hacker can exploit it. If you have the worlds most renowned secure, then the best hackers will break in at some stage while the wannabe hackers struggle to threaten their way out of a paper bag. However with some people, they need gold bullion and jail style security while others wonder why they need it. People can recommend you do this or do that, and some recs are excellent while others are not quite but almost hilarious but at the end of the day, if a child can hack into high security places, our devices are not so hard to get into. That said... we can run paranoid while there may be no threat at all. If you are concerned, just be careful of what you do with your device. Myself, I use it for every day communication and have not yet used a credit card on it with no real need to.

3. Even the greatest have not updated their OS. The Motorola Xoom promised one from purchase yet people were moaning long after the stock sold out that it never came. Granted it surely must be true that certain companies are quicker to advocate update releases than others. But the higher paying vs the cheap low end thing isn't something to run with either. I have a very cheap quad core tablet and that has just had a firmware update from last week and as far as I can see, it's an almost brand new device, market wise so it seems the update from them was fluid. Again, that said, the updates seem to be more about the OS running well, with the hardware and app capabilities than security although I dare say there are some inevitable security fixes in there too. My quad tablet was sluggish to some extent and a bit crashy but so far, it is fine after the update although I have only done it a few hours ago... everything me and the kids have tried, has either worked better of been flawless. No sign of lag yet anyway.

4. In-app advertising can be dangerous for a few reasons i guess. but the reality again, is I think any file can have dangerous code attached and configured in a way that the OS or security cannot smell it. Of course there is the ability of spam links to scam sites. There is also false flag things that are or maybe are possible too. For example, using x file with y file and requesting a cup of tea from z file can make a security team think your couch is about to disappear and your granny is about land bump on the floor, when indeed an app just wanted to execute a command using an ancient method of pressing Q. This is something I learned in windows based operating systems where using certain dll files with certain other files can trigger an alarm, as innocent as the intentions were. I built a website not so long ago and called some iFrames in that had no < head > or < body > tags. the pages worked perfectly but some chinese company employed to protect a british isp flagged the site as a security risk and blocked any visitors from viewing it. Thankfully, long gone are the days that visiting a website would fry your motherboard.

On your remaining comments.. seems like wise advice as of course there are scammers out there who will give your granny that bumpy ride off the disappearing couch onto the floor or steal your account and all those types of greed based madness which is a shame because it ruins the experience of say if a friend is trying to build an app and they ask you to give it a go, you are somewhat rightfully not willing to play ball.

FYI I have been around computers for a long time but am by no stretch of the imagination an android expert at all. I hope what I have wrote above is helpful and not by any means, wrong. I have not long posed the question about rooting and security as I do not qualify understanding the realm at all. I dare say it is a huge question, to some extent.

Also, security risk aside as no smartphone tablet or computer escapes that realm, Android for me is the best device, then IPhone, then Windows Phones, then Crapberry. I would never purchase the latter three.