I say leave the kal-zul part for last, and research it in your own time. I`m sure you`ve seen the "strange energy readings" message. This means that other empires are close to completing the project. What happens is that you research Kal-Zul artifact, and you`ll be able to built what`s called the "ultimate weapon". However, there are two parts to this beast that you`ll have to research one at a time under the "projects" link. After you complete the first part (it requires 250 turns and some cash you must put into it), you`ll have the option to activate it after 24 hours and start on the 2nd part. Then "strange energy readings" will start coming from your empire.
Then, 450 turns and more donated cash later, you can activate the 2nd part instantly. Then you have to be able to survive 48 hours without losing all your planets and without being defeated under 500,000 power rating to win the game. However, the downside is that you only get 1 hour damage protection, and everyone and their grandmother (except for fedmates) will be able to slap you without any kind of attack restrictions.
BUT, you don`t have to activate to win. If you suspect that someone else will be activating a UW in the near future (you see energy readings from a player at 800 million power rating for example, which can be very hard to beat depending ), you can activate yours first and INTENTIONALLY lose under 500k pr (don`t worry, only the project is lost) and force him to start over. A lot of times this will either force him to abandon his efforts or go into debt just trying to research it again.
But, in addition to this, you also get 2 free big time capsules that give you 100 free turns each. For your efforts. :)
Just something to keep in mind if you want to prevent what looks like a very hard battle later on. ;)