Installing a SPOA will pretty much require you to disconnect the brake lines in order to position the axles. You MAY be able to keep the brake lin intact if you are careful about removing the springs. That said, if you have to disconnect the brake lines, you might as well add brake line extensions. The bleeding process will be the same. Speed bleeders at each wheel work best to make the job easier.
There are self-aligning bolt-on SPOA kits. Unless you are only mall-crawling your Samurai you really want to weld these in place at your first opportunity.
ANY suspension lift (spring-over or under) will introduce bump steer. Bump steer is when the steering wheel "twitches" when you hit a bump or pothole. The higher the lift, the worse bumpsteer gets. Do a search at
Ack's FAQ for
bump steer for an explanation of bump steer.
A soft ride in a Samurai is like a pillow fight with sandbags. I have no personal experience with the YJ spring conversion, but a LOT of folks swear by the improved ride. Someday I might make that mod...
I hope that this helps!