Do Medikits used in "contact" get the +1B bonus from being used in a 3+ person fireteam or not because "contact" means they're not being used as a BS Weapon? It's seems like RAW they would lose the burst bonus (though it's written kind of funky)... but it creates a kind of weird situation where you'd rather shoot it at a person from millimeters away than walk up and inject them.
Yes they lose it. Assuming BS11, PH10. You're on 50% odds to succeed or kill if you do it in contact and if you shoot you're on 33.25% to kill them, 9% to miss completely (so 42.25% to fail at healing) and 57.75% odds of succeeding. But if you're a Dr with WIP13, then you're on 65% odds to succeed and have the opportunity of rerolls. If you DIDN'T need to roll to hit, but still got the burst bonus in S2S then B2 Paramedic would be on 75% odds of reviving: so having a DR wouldn't be really worthwhile at all.
For rules references, we have: https://infinitythewiki.com/Fireteam_Bonuses In the Active Turn, the Team Leader can apply a +1 bonus to the Burst (B) value of their BS Weapons, including Throwing Weapons but excluding Technical Weapons. https://infinitythewiki.com/MediKit Used remotely, a MediKit is considered a Non-Lethal BS Weapon. If the user passes a BS Attack Roll, applying the corresponding MODs (for Range, Cover, etc.), the target will perform a single PH Roll. => That is to say, the MediKit is considered a BS Weapon only when used remotely, so it is only then that it is applicable for the bonus.