I completed this swap recently myself, yes you can reuse your coil packs, they will work just fine. The major things involved in this swap are as follows:
You will need to use the 96's oil pan, it has a sensor that screws into it that a PI engine doesnt have. You will also need to drill and tap the PI intake to make room for a sensor that the 96 has and the PI once again doesnt have. You will need to re-use your front cover off the 96 to be able to bolt up your coil packs and their brackets, the PI engine has a belt tensioner in the way of the coil pack brackets. You can and will reuse your ecu, but i reccommend buying a flash tuner and having a tune put on it for you. There is one other connector that is a little different then the PI motors but I cant remember what it is off the top of my head. Essentially you end up reusing all your old wiring and nothing off of the PI engines harness (if you even get the PI harness). Yes your old T45 will bolt up to the PI engine with no problem provided you use a flywheel and clutch made for the T45 and not the 3650, if you have any questions about this feel free to let me know, like I said I just completed the swap.