Budding
It is a very interesting angle that you are approaching this from. You say you aren't getting in to flying for the money or for job security. That being the case I can only assume you are getting in to it for the enjoyment of flying? If that is the case, forget airline flying all together, go get a private pilots licence and an aerobatic rating and rent/buy a Pitts special or something similar. And keep your secure job in the city earning good money. No brainier for me! And it'll be far more fun than airline flying!! Trust me!
However, taking your points one by one.
1. Maybe you'd be happy flying a dash 8 around for the rest of your life and doubtless there are some pilots who are very happy living in the regions of the UK doing exactly that - and good luck to them. They are probably better pilots than many jet pilots because the dash is a more demanding / less automated aircraft. But most people want career progression which means moving on to jets and as a result earning more money and getting better benefits with bigger companies. I accept that doesn't fit with your plan (although I honestly can't fathom why someone would place limits on their ambitions at such an early stage).
2. As a logical person you will no doubt know how volatile the airline industry is. Like just about every airline out there flybe has an uncertain future, but it's more uncertain than some others because of the niche market it operates in. If you don't care about getting made redundant and the risks associated with that because you can just pick up your old city job again, fill your boots. But it would be a terrible investment of your time and money in my opinion. As investments go, it's as risky as they come, because you won't be able to get another flying job easily if all you have is a dash rating. Don't get me started on paying for type ratings .... because what comes next is paying for the 500 hours you'll need to go with it (an A320 rating on its own without hours is worthless and won't get you an interview anywhere). People do it but it's very controversial. Paying to fly fare paying passengers around?! What's next? Paying to fly for a year or two?
3. Again, baffling. Never ever met a pilot before in all my years who doesn't care about job security. Someone willing to pay for a ATPL/MPL and or type rating with dubious employment prospects and high risks. An airline accountants wet dream by all accounts!
4. As I said before, getting a command is just something you cannot put a time frame on. Some people who get in to an airline at the right time wait 3 years, some wait 10. It is in a constant state of flux and changes almost daily based on the economy and the commercial flying program. You also have to pass a command course as well by the way - not to say you wouldn't but command is not something you just 'get'. People do fail. They might also require you to move to a different base for your command.
I think a job at flybe (or any other airline) would bring you enjoyment for at least a while because most new pilots love the job to start with. Even after 7 years I still enjoy the flying. What I don't enjoy are the consecutive early starts, missed social events, fatigue, constant pressure on terms and conditions etc. None of the friends I made at flying school would tell you they 'love' the job anymore. Most enjoy the flying but hate everything that goes with it.
Generally I think there are far too many people who start a flying training course throwing caution to the wind and just hoping for the best. But look. If you can honestly afford to write off £100,000 and take the chance without it really affecting your finances and walk back in to your old job if/when it goes wrong, well, what can I say?
In my opinion the lowest risk entry point to commercial aviation is the BA future pilot programme. Flybe is a high risk/low reward entry point for all the reasons that have been mentioned. Don't assume if you are made redundant that CTC or anyone else will 'find' you another job - they won't. You will have to move heaven and earth trying and might well have to make good on your rhetoric about going back to your old job in the city - so be prepared for that!
Really though, if it's all about enjoyment and not about money, go fly light planes and forget working for an airline!