Swapping shocks is quite easy. Only obstacle is that depending on exhaust type, the muffler may be in the way. Other than the exhaust, only 1 bolt and 1 nut/shock and they are off. If you have a centerstand it doesn't matter how you do it but if you only have a side stand only remove on shock and replace it with the new one, then do the other.
Lowering the front end wouldn't be mandatory but it would be recommended. Check the stickies in the suspension forum. There is one called "procedure on lowering blocks". You can lower the forks internally by installing some homemade spacers. Or, as garrett mentioned, you can by a spring kit from progressive that comes with lowering springs, either way works. The kit runs about $100
You can lower them by raising the forks in the trees but to do that you need to remove the air crossover and plug the holes with weld or jb weld or epoxy. Even if you lower them internally, I would remove the air crossover, plug the holes, and run the forks with no air, 15 or 20 wt oil.
It not really recommended to lower the front end without replacing stock springs.
