Lost key, unlockable trunk, weird steering

I recently bought a BMW 525i -88 (in Sweden),
the guy I bought it from only supplied me with one key I'm assuming it's a spare key since it won't fit in the passenger side door or the trunk..

Is it possible to buy a master key or can a locksmith make one?
Or do I have to change the locks, how much will it cost me?

Also the trunk won't lock when I lock the car at the driver side door
Anyone know what could be wrong with the trunk-lock?`

I checked it and found a white cable leading to the "lock"-mechanism
in the middle of the trunk that had been cut off, I could see where it used to be connected but I don't think connecting it there again would help beacause it wasn't leading to anything past that point.

Also the steering feels weird, when I turn the steering wheel the wheels don't start moving immediatly, it takes about half an inch to an inch of "turning" the steering-wheel before the wheels start turning, a friend of mine said thought it might need a new servo, or possibly repairing the old one, how can I tell if my
servo needs replacement or if it can be fixed with some repairs?

When I bought my 525 I only got one badly worn key. I went to a BMW main agent with my log book as proof of ownership and they ordered me a new key from the chassis number. If someone has change the lock(s) then this method might not work.