These are just my thoughts, and in no way should you do as I do. You gotta do what works for you.
First thing - Get a good gun. Train with what you use the most, and most likely to use. I brought two, one for backup - and indeed I needed it, as my first gun shit the bed after the first hundred rounds due to sheared off bolt lugs.
So I normally use an AR as a primary. I brought two - the first being my NEA PDW, and the second being a Stag Carbine.
My secondary is a G17 with a threaded barrel and a Streamlight TLR-1 light with XS Tritium Big Dots. For mags I use a combo of Pmags and Lar15. The Pmags are like butter so silky smooth, and the lar15 has the capacity for 20 rounds when done up properly. Of course you always download by 2 if loading full 30 rounds. For optics I generally use Aimpoint - H1/T1 or the PRO. Sometimes I might even mount an ACOG.
For this course I used the PRO and it is good (I wanted to see if it would handle the snappiness of a PDW). The Aimpoint PRO stands for Patrol Rifle Optic. It's basically an enhanced M2 with a QRP2 mount prepackaged. For the pricepoint, you should be asking yourself...WHY THE HELL NOT. I will review this awesome piece of kit another time.
For kneepads the most comfortable ones I have ever used are the
Arc'teryx ones. For gloves, I wear whatever tactical ones I have lying around, Oakleys, Blackhawk, Outdoor Research - whatever. This particular course I used HellStorms. They worked. I've resigned myself to the fact that gloves - like boots - are sacrificial pieces of kits, no sense in babying them. Just use the shit out of them, and get new ones.
Regarding boots - My go to are the Lowa Desert Zephyrs. I've used these in the desert, in the tropics, in the urban, and they are the shizzle for course-work.
So the Wx for the course was a mix of inclement and fair weather. Most of the time, the Arc'teryx LEAF Alpha was used to sheer off the rain and the wind. I wore this jacket both under and over my armour. Of course, wearing the Alpha over the armour made me look like the Michelin man, but whatever, this isn't a fashion show. Because of the mixed Wx, when it was warmer and the rain ceased, it's quicker to take the jacket off than to take off the armour, then the jacket, then putting the armour back on. It gave me no problems at all for accessing waist workspace tools.
My Sling recommendation - BFG Vickers sling for carbine. For PDW that is 7.5" I would go with a MS2 or MS3. But that BFG Vickers is very versatile and works great. What I do is mount the forward point on the "inside" of the gun, while the rear mount would be on the "outside" part of the butt stock. This actually gives me more space to do transitions, and easier too.
This is stuff that I use normally anyway, so its not like I'm trying this kit out for the first time. What I would recommend is to use what you have, spend the extra money on ammo, optics, and training. Then buy the kit as you "need" it.
OK so what didn't work. Shitty ammo. Don't buy shitty ammo. That's it. There is that question about the PDW that screwed the pooch, but thats a direct result of using steel casings in a high-pressure gun. The warranty guys said that it was actually a metallurgical fault of the bolts they manufactured a batch of, after sending me the new one, it seems to be fine.