Re: financial records
i've kept one for about 7 years since i was 18 or thereabouts. obviously it became more and more important as i got older, started earning and spending and since i use my debit card for pretty much everything now. i update it every few days with my spending so that i can see how much i'm spending as the month progresses and it's usually bang on with my statement. i also forecast months with my fixed expenditures etc.
i think it's important to keep track of how much you spend, where you spend it etc and to forecast how much you will save given your average spending. and since i put more of my own details in about what i've bought than appears on my statements, it can be really helpful later on.
there are also programs out there that have everything in terms of letting you manage multiple accounts, credit cards, categorise everything, even scan in your receipts so that you have a record of them.