My personal 2 cts.
1. No you're not too old. Some airlines clearly prefer younger candidates, others don't care. In the corporate flying world they actually prefer older chaps.
2. Nobody cares about the theory. You will not be better or worse educated as a modular. The theory is too easy to be considered impressive so everybody gets 90+% average these days (especially with the QB)
2. Yes, your application will be binned instantly when you apply to an integrated only position. And quite a few airlines have CTC/FTE/ etc as preferred integrated suppliers. There are, it seems to me, less chances as a modular student to get into the big jets, but it is not impossible at all.
3. Nobody cares about your hour building. Just make sure for yourself, that you don't waste the hours flying circles around your hometown but actually learn something. Nobody checks your logbook for signatures. The CAA can check it if they want to by auditing your friend's airplane log if they desire.
4. Don't know. This bonding story was floating around when I started my training 5 years ago. Might be happening, might not? That said, aer lingus is by FAR the better employer (really, world of difference) so who gives a crap that they fly airbus? You're on auto pilot anyway so you might as well be comfortable.
As a modular student myself, I would like to add the following. I am currently only flying SEP airplanes around as a part time job in the weekend, trying to scrounge up a few hours here and there to hopefully move on eventually. I have friends that got a bonded TR on a big jet, others that paid their own, and others that paid for TR and line and are now actually employed somewhere else. A few are still instructing, and a single one never got a job and moved on with his life after a lot of heartache. What I want to say is that nobody knows what will happen in your career, and nobody in aviation is going to give a crap and go out of their way to hire you. In the end, it all depends on your perseverance and unfortunately quite a bit of luck/timing.