(ps. is the Mercs 2 glitch where you fly over the collectibles easy to pull off? I hope to 1000 the game eventually)
Stupid easy. All you have to do is find 30 or so, then save/re-load and fly a chopper over them. They will re-register. I'm not sure the logic behind keeping those numbers though, because it doesn't save all of them. I found about 60 or so legit, and then kept flying over them, sometimes by accident. At the end I had 120+ of the 100 items.
The Baby Billionaire thing is easy with the winching challenge glitch. After about the 50% completion mark, you can bump the bet past its limit by doing the challenge without break. In the end I was betting like $30M. And there's also the winching glitch itself where you fly straight up, release the package, then fly away as fast as possible: once the package leaves Havok's perception area, it stops falling, is considered to be at rest, and the bet is won.