A few thoughts, based on what I read in the last couple of pages and my own experience:
Horseback anti-tank = pure awesome. I remember galloping after tanks, firing rockets at their rear, in the mission where you have to stop a tank unit and their commander from reaching a fort. Who said proper cavalry was dead?
I can't bring myself to use the sneaking suit and derivatives much: I find visual camouflage much more valuable than silent footsteps when crouching. Because on the one hand, once you're close enough, having to sneak-walk is just a small inconvenience. And on the other hand, I don't abuse the fast-forward cigar thing since it feels cheap to constantly skip to sunset. I wish the game rewarded operating during the day, since it's the more difficult choice and there's no downside at all to taking the easy road. I've been seeing an increased amount of NVG-wearing soldiers lately, however, and I wonder if it's a coincidence.
Backup, Back Down mission: I had D-Horse, and merely picked a spot along the road the vehicles drove along and used a combination of C4 and the GROM launcher, in that order. I missed the Electrospinning specialist, though, so I need to redo that mission to get him and gain access to DD's first armour upgrade.
On the subject of C4, it's been incredibly useful to blast critical things like antennae, generators, radios and AA radars. It's also handy to scatter around large bases, and detonate to draw enemies to investigate, ideally out of your way as you make your escape.
Hellbound mission: I infiltrated the first half of the base in the wee hours and through a sandstorm, and morning caught up with me in the second half. Camo and a lot of prone crawling is vital to remaining undetected in broad daylight. Stick to the shadows and grass whenever possible. The left-side door of the bunker-hangar was locked, but the right-side one, the one at ground level, was open (blue). If guarded by two soldiers, which I managed to sneak past. That's how far I've gotten, to date.
On the subject on neutralizing people non-lethally, short of fultoning, holding up a guy and telling him to get down semi-permanently neutralizes him. He won't get up unless someone finds him or the base's alert level goes up. I've been doing a lot of hold-ups (and without sneaking suits), mainly to get info and save tranq ammo.