[General Questions and Answers] codQuore:
At a guess I would say, for browsers that are built in to the OS, there will be two ways this can update, via the OS update and independently. The OS update would be a total OS replacement that is not automated and you would need to use a built in checking feature (if available) or manually check yourself periodically. Browsers that you add yourself will be offered updates from notification unless the ability to auto update is allowed then it should happen seamlessly of course letting you know. Google "android chrome update" to see something along the lines of what the update history shows.

Yes, you would want to update but I would recommend having a read first as on any computer device, an update can be flawed or give more problems than it's worth. Although more often than not, an update should be an improvement on performance and stability and of course for security.

If you are working blind, then do an update and assume security improvements are happening and go for it. If not, then you will know what is happening. I have never gone to the lengths of checking an update list before updating for android, but with pcs I do depending on what is updating, check what the update is worth and how people are getting on with the update. I did beta testing for years (hence the knowledge of flawed updates and reluctance to do the updates) so for me it's one of those do you risk it scenarios.

Sadly as I said above, we are never safe from hacks but with some hindsight and genuine attempt to protect, we are safe from the majority. For me it's 90% "what are you worried about?" and 10% "I don't blame you for being paranoid!"

As for the preference of buying google branded devices, the foundation of an android release is surely never set for these devices "out of the box" so to speak. I would assume that the team who look after these devices have the same process of having to streamline the OS thereafter before they can release it for their device update. This is somewhat proven by people wanting to put a custom rom on their Nexus and such. For some reason, people aren't happy with the normal rom and want or need to replace it. naturally, it is easy to think a nexus device for example, is closer to home and should by rights get updated a bit quicker than my Ampe tablet but in some respects I think this could be a bit of swings and roundabouts, again depending on the company and their apportioned team force to output the update. Yes you should be better off with a more directly linked device, to google but in my opinion, the concern is not a great one. You would be better off thinking about your budget, what you can save and ultimately do with the extra cash alongside the knowledge of which devices and companies actually do spend an effort on looking after them.

I'm in no position to afford these devices and if I were, I would rather throw my money in the bin (or spend it on my loved ones) than give it to the highest bidder.

So in the end, yes updates are 99/100 important and should be done. Be careful of what you browse and do all secure data passing before you go out on the internet highway and risk getting robbed. It is probably safer to "remember my password" to avoid future keysniffers than worry about indepth data mining. Of course, anyone can give you a sniffer but data mining is more clinical, I would say.

Finally, i wouldn't worry about these things too much but as concerned as you are, do some research. But do remember that in one hand, the UK government said "the internet isn't safe so we don't use it" yet on the other, the majority of secure usage is 'watched' by paid professionals for banking and such and is alot safer than you may think aswell as protection for credit card fraud and such.