I am looking to purchase a Bushmaster "Patrolman's" rifle flattop and want to set it up with optics, light, and sling.
1.  Any downside to "patrolman's" rifle?
2.  Looking at Aimpoint or Eotech so far.  What mounts will work with each along with back up iron.
3. Flashlight set up?  Surefire I assume.
4. Tactical sling

I want a simple lightweight gun for Police Duty use.  I don't know much about mounting systems but want to make sure I get it right the first time.
Thanks.

Simple and lightweight, Hmmmm

Go with the Aimpoint M2 over the EoTech - battery life is MUCH longer.

Personally I'd go with the A2 upper and use the Aimpoint gooseneck mount and Railgrabber mount.  This will mount the Aimpoint forward (better for quick target aquisition), but allow immediate use of of the iron sights should something go wrong (this is called cowitnessing).  With the A2 carryhandle you can never 'forget' your irons.

Sling?  I like the Tactical Taylor, but more and more people are swearing by the single point slings.  There are several you can check out the different ones here: groups.msn.com/TheMarylandAR15ShootersSite/slings.msnw

Definately the Surefire for a flashlight.  For a mount try the one mentioned in this article: groups.msn.com/TheMarylandAR15ShootersSite/taclightnotes1.msnw.

Hope this helps.

That's actually the set up I have.  I had it sent to Kurt's Kustom Firearms to have a fake flash suppersor pressed on the end, just for looks.  I wanted a full 16 inch barrel.  The only thing I regret is not having some sort of compensator/supressor for follow up shots, but so far it hasn't been that bad.  I've fired a friends with a compensator and found my follow ups much more accurate so I'll wait until I get that preban lower for that set up.

I went with a single point sling.  I found it great for weapon's transition from carbine to side arm or strong side to weak side shooting.

Optics-wise I have an Aimpoint on a KAC Offset mount with a KAC 600m back up sight.

Next on my list is a KAC RAS with a vert grip.  Light wise I'm unsure of yet.  I may mount my surefire 6p or get a new one just for the weapon.  For now I hold the light, that way I can just use the 6p with either the Carbine or my sidearm.

As far the carry handle sight goes, you can also get a flip up rear sight that is spring loasded so you can't accidentally push it down.  I would not leave a rear sight flipped down unless it is for storage.  Cowitnessing is the fastest, most practical, and safest practice to use when using reflex sights.  Personally I would go with a flattop with a removeable carry handle.  You can still use any carry handle mount and always have the option of just using the flattop.  It's better to just have the option.  The key is to be able to keep the reflex sight farther out from your eye than a normal scope.  This enhances peripheral vision and prevents eye strain.

A single sling is great, I use it personally.  However i also have to use a Blackhawk weapon keeper on my pistol belt to prevent the rifle from swingin around too much when it hangs.  With a three point sling you get much less free swinging, although I still recommend the weapon keeper just to keep the rifle secure when not in use.  Blackhawk also has some tactical slings with elastic to keep the rifle cinched to the body but still allow it to be rapidly deployed.

The Surefire M900 is a great light.  It is the vertical foregrip light.  It has LED's to act as navigation lights and a powerful tactical light as well. It has a built in vertical foregrip with all the controls built into the grip.  You don't even need a complete RAS to mount it.  GG&G, dvanced Armament, and falcon industries al make rail mounts that bolt onto the standard foregrip.  Fobus also makes a replacement foregrip with only top and bottom rails that is at a reasonable price.  The Surefire M900 is something I would recommend you seriously check out.  The M500 series is also good if you don't like vertical foregrips.  It does the same thing, but is housed in a replacement standard foregrip.