I don't think these are buzzwords at all, but rather important political concepts that people take for granted at the moment and will miss once they're gone. As for what they mean to the average man on the street:
Sovereignty - having a UK government responsible for running the UK, having all the instruments of state (police, army, civil service) report to it. E.g. having the British army that can be sent around the world to defend Britain's interests (e.g. Falkland Islands) on the say so of our Parliament and not an EU army where we'd have to get permission from Brussels to defend the Falklands or intervene in Sierra Leone.
Every time power has been pooled from the local chieftain going in with the next tribe or a few lords swearing allegiance to a baron right up to the amalgamation of the british isles into the uk (Ireland opted out, mostly). And now the combining of the states of europe into something bigger.
It's the way the world has progressed for thousands of years, are you saying this point where the UK is now is perfection and we should just stop that progress here?
Accountability - having the government held to account. Doesn't matter how powerful a politician is in this country, they can always be voted out at a general election (ask Michael Portillo or Ed Balls). We also have Her Majesty's Opposition and Parliament to also hold the government to account on a day-to-day basis. Who is holding the European Commissioners to account?
That's an easy one, the same elected officials who appoint the head of the DVLA, and that ******* has far more influence on my life than most of the EU!
Transparency - being able to see and understand the day-to-day workings of government, not having deals done behind-closed-doors in backrooms like the ongoing TTIP deal. Having a register of member's interests for Parliament and sanctions for those MPs who do not declare an interest. Understand that while our system isn't perfect, corruption happens just like everywhere else in the world, it is a good deal more transparent than the way the EU government is set up, where the error rate in the accounts is still too high for the auditors to give their accounts a clean bill of health.
I don't doubt there is corruption in the EU, same as there is in local councils and Westminster. There isn't any systematic lack of transparency in the EU however, certainly no more so that in UK institutions and some of the things you mention to tackle corruption in the UK only came about in the last couple of decades - due to rampant corruption.
Why not write to your MEP about it?
Also:
TTIP is a complete red herring. Everyone will see it and vote on it when it's done. No trade deal has been done in the open, it would be unworkable.
EU accounts have been passed by auditors every year. I've never seen any audit not have some comments, but they are always passed so long as there is no serious concern. If there was a serious problem the auditors would have refused to sign off on the accounts.
Saying there is a problem with the EU accounts on this basis is as wrong as saying a scientific theory is not fact only a theory - it's a misleading use of domain specific language.