I believe its a requirement these days to have a TAP (total amount payable) on the finance contract, regardless of any lines the salesman/finance company attempt to spin, this is the bottom line that you should be interested in.
Some finance companys will charge you extra to get out of the loan if you do it too early (or at all) and some charge you more to put extra money in, this should all be in your contract though.
In regards to how much have you got left to pay, you should be able to ring the finance company and ask for a payout figure and outstanding amounts, I've been able to do this with any previous loan I've had , be it store finance on household items or finance for a car or house loan.