I have installed lowered springs into my R100 which is fitted with Rx2 struts (they bolt straight in and have a slightly larger brake) I also run my stock 14 inch rims and have more options for slightly larger and wider rims but that is limited to the offset so as not to hit the brake caliper... pics here,viewtopic.php?f=5&t=12719&start=20
You can use the original struts and purchase lowered springs (they are made to be more rigid and you can buy them for about $200 a pair AU new)... They are a far better ride then cutting the original springs.
With the rear leaf springs you can either use lowering blocks or get them re set which is the better quality option as they can also re set them to exactly how low you want them...
I purposely wont get my leaf springs re set until I have the car in full working order with the wheels on it and then Ill get them re set to exactly where I want the car ride to be/ "or sit"