John,
If the slide can be screwed completely off the leadscrew, then by screwing out the one you said, the one nearest to you, then you can just pull out the tapered gib. Do NOT touch the back gib screw.
Once the gib strip is removed, the crosslide can just be manouvered off the dovetail, giving you access to drop the said bolts out of the holding ring.
To put back on, remembering first to have your bolts in the retaining ring, engage the leadscrew first, then insert the gib strip and tighten it up until it hits the back adjusting screw, do not overtighten. If you do it right, your gib adjustment should be the same as it was before you took it off. Take the opportunity to pop a bit of oil in there while it is off.
A couple of minutes round trip.
It is not recommended to hold milling cutters directly in your chuck. The hard chuck jaws coupled with the hard material of the cutter, plus the very small contact area between the two is not condusive to get a good holding regime, and normally the cutter will move in and out of the chuck jaws if any sort of cutting pressure is applied.
Really, you should be looking at maybe an ER collet set, that mounts into the morse taper fitting of you spindle, and use a home made drawbar to hold it in position (threaded rod and a big washer is all that is required).
You could get away with just 3 cutters to start off with, 3mm, 6mm and 10mm (or approx imperial equiv. 1/8", 1/4" & 3/8"). Don't play around with any smaller or much larger for the moment, get used to what your machine can handle first. Once you go above or below this range of sizes, the costs of cutters usually start to rise dramatically.
It might take you a little longer to machine out say large slots, but you are not paying for your time.
If you can, get the disposable ranges, they usually have three flutes and can be used in both end mill and slot drill configurations. Later, when you have a little more experience, you can invest in the specialist end or slot drill ranges.
Doing it this way will keep your pocket contents a little more user friendly. You will definitely be breaking or dulling cutters while you are learning to mill, and by buying the cheaper ranges, you won't feel as bad as if you break say a solid tungsten one, costing a quarter of a weeks wages.
You could go down the cheaper route for holding your cutters for the time being. Buy a few cheapo blank MT3 arbors, and carefully bore them to fit your milling cutters. Then put a grub screw in the side to hold the cutter in there. Grind a small flat on the side of the cutter (it might already have one on there) for the grub screw to hold against and stop the cutter moving.
John