Travel while waiting for BRP - Tier 2 extension

[xp2012]

Hello everyone, sorry if these topics have already been covered in the past, but I haven't been able to find something similar:

I need to extend my Tier 2 G and I managed to get a premium appointment on the 8th of June (with ENORMOUS difficulty, logging onto the site at midnight nightly, etc). I didn't realise that it then takes at least 7 days to get the BRP (or more?!!), and booked travel for a conference and subsequent vacation already on the 12th!

In theory, according to the rules on the website (34K) they shouldn't penalise for this in Tier 2 category, right? (NB: there is also a clause about the possibility of travel on a different passport - another option for me - here). Especially if the decision has already been taken and I'm just waiting for the BRP, shouldn't I be able to leave the UK, have a colleague or the secretary at work sign for the BRP when it arrives, and courier it on to me elsewhere? I would appreciate advice on the following points based on everyone's experience:

1. Is it possible to re-enter the country on the old EC which will still be before the expiry date IF the BRP appointment already took place (presumably not - do they stamp it as "cancelled" right there and then, or does it come up as such in the system?)

2. I have dual citizenship and can also use my second passport as per above; is it advisable to do so to enter the UK again, or does one's name get flagged up in the system anyway - does anyone have ideas?

3. Finally, is my original idea of having a colleague send on the BRP to where I'll be (in Canada) and then entering on it when I come back just too risky in general?

Many thanks!

[geriatrix]

1. No. All leaves issued in the past are now invalid (automatic invalidation).
2. No. Leave to enter / remain is granted to an individual, not a passport. You are the same individual .. irrespective of the number of passports you may possess.
3. Risky, e.g. -if it gets lost in transit.