that sounds like your brakes are unwell, change the fluid for a start!!! have you got cheap pads on? et some genunie vaux ones on! if that don't work look into your master cylinder and abs unit. the standard brakes are very good
if you need a replacement powersounder for the alarm, i have one i have just taken off the '99 omega i am breaking you can have fror £20 posted pm me if your interested
its pretty straight forward to do so don't worry just take your time and don't rush or you'll break somehting. you do need to take more off to get to them than you'd think, don't be tempted to do it with out removing the inlet manifold as you won't get the gaskets on tidy and they will leak again
you have to be careful, as it depends how it was connected to a live. i've had cars that its connected to an ignition live like the fuel pump......
i can normally get in mine when teh bats flat or disconnected through the boot which you can open with the key if you turn it an extra bit, but that does depend on if you've locked the ski hatch.. if not then you can reach the seat fold button and climb trough to open the bonnet
silly question but have you checked its al timed up correct, thats what the cam sensor is there to keep any eye on so you could be chasing the syptom and not the cause