1) Try having just one bullet in the layout, and ticking "Destroy on startup" under Attributes in its properties.
2) Python script is still in early days and I don't think it has per-instance manipulation yet; the primary way of coding games is still via events. Your code is trivially easy with a create action, set X, set Y, destroy, set X, set Y, etc. If you need any help with that, let me know...