What are the main differences between the Flare Gun and the Detonator

The compression blast range appears to be slightly shorter than the range of your actual flamethrower, from personal experience. You can compression them anywhere within that range and you'll reflect. The angle that it gets reflected back at is dependent on where your cross-hairs are aimed when you hit the compression blast.

Additionally, for grenades, there appears to be some determining factor with return velocity depending on your distance from them. I can't find a lot of info about that though.

Rockets will travel indefinitely until they hit an object. Arrows seem to function similarly to grenades, but less noticeably so due to their natural high speed and lack of "bounce".

In regards to lag compensation, the compression blast is NOT lag compensated. You're going to have a harder time reflecting rockets / grenades / arrows if your lag is higher, especially when dealing with the higher velocity ones like the Direct Hit rockets and arrows.

Edit: As per the link in the comments, edited the above to indicate that the compression blast is NOT lag compensated.

It's hard to say "when" you should compression blast. It's a function of distance and velocity, rather than time from fire. With any projectile, it's nearly impossible to reflect at short range without some sort of luck / godly reaction speed. At longer distances, the Direct Hit and arrows can still be relatively difficult to reflect. Again, it's about the distance, not the time before it hits. The best way to get a feel for it is to play it and learn it intrinsically, not go by a paradigm that there's a hard rule for timing it based on seconds.

From the best of my understanding:

• When you scam somebody, you find a new, guillible TF2 player who has earbuds (or an unusual, or another very valuable item), lie to them about their value (tell them that they are worthless) and offer very little for it. Offering a Paypal payment and then failing to go through with it (and viceversa) also counts. Here's SteamRep.com's definition:

  A scammer is anyone that uses deception, thievery, lies, or anything that is underhanded to take advantage of or steal from another trader. See below for more comprehensive list of what qualifies for SCAMMER status: (snip; non-comprehensive list folows)

  • Charge-back or Reversal (buy an item from the store, trade it away, chargeback purchase)
  • Quick-switching items (offer to trade one item, trade a visually identical/similar but much less valuable item instead)
  • Receiving the item and not paying (offer to trade for cash, get item, don't pay/pay and get refund from PayPal/etc.)
  • Spycrabbing and then not paying (gamble an item away, lose and keep the item)

• When you shark somebody, you find a new, guillible TF2 player who has earbuds (or an unusual, or another very valuable item) and tell them that you'd like to have it; you'll even give some weapons for it. The sharker banks on the new player being wanting for that annoying bow and arrow thing enough to part with a bunch of pixels in exchange for it. The player doesn't know better and agrees to the exchange, but the sharker didn't actually lie so it is not scamming. The trading "scene" places the blame then on the gullible player for being, well, gullible and agreeing to a bad trade. Obviously he should've known about steamrep.com and backpack.tf and tf2outpost.com and why the hell buds are worth that much money anyway.

• When you lowball somebody, you try to trade an item for moderately less than what it's worth. Typically used by sellers when they don't feel like accepting somebody's offer. This is also not scamming.