Changing the sights should be fairly simple with the right tools. The problem is that a sight pusher will probably cost more than what you can pay to have someone do it who knows how.

As for the laser, I recently added a LaserMax rail-mounted laser to my Glock 20, and it seems to be a nice quality item that holds its zero under heavy recoil, and is easy to turn on as you make a proper draw (trigger finger extended along the frame).

If you feel the need to hang even more crap off of it, the laser has its own rail that you can hang a flashlight on, though I don't know where you would ever find a holster to accommodate all that. I had to make my own for the G20.

I recommend the Streamlight TLR-2. They are pretty reasonable, and better than any surefire product I've ever used. I bought mine about 5 years ago, and have gotten a lot of use out of it. The switch is very intuitive and user friendly. It is also great on an Assault Rifle. I had mine on my M-4 while I was in Baghdad and used it frequently. I don't do much shooting with it, because it gets boring putting all your bullets through the bullseye after a mag or so. Yes a laser does make it that easy.

My opinion on night sights is they are a waste of money. If you can't see white dot sights 1 foot in front of your face, what makes you think you can see your target at 8-20 feet? They cause you to focus too much on your sights and not on your target. But that's just an opinion, clearly millions of people disagree and buy them.

Do not use Insight M6 Laser/Light combo it will not stay attached to the gun during repeated fire. I tried repeatedly to attach my Insight M6 laser/ligh combo to my new Springfield XDM 45 4.5 and about every third round the laser/light would just fall to the ground. Granted, this would not be good in a real self defense situation. I attached the Insight M6 laser/light combo to my Gen4 Glock22 and re-zeroed my laser @ 10 yards and everything works fine. The laser stays zeroed even when I un-attach and re-attach the laser/light combo. The rail attachment grooves are just not deep enough on the XDM 45 to hold the laser/light combo in place under repeated fire.

I would get the Streamlight like the user above suggested and if you would like to get sights go look at Welcome once you buy the sights they install them for free you just have to send your slide to them. He does a great job and you can ask him to recommend you some sights and he will gladly help.