Yes to +1 Strength and Toughness when a DE IC takes a reaver jetbike.
DE Faq. V.4.0.1
As to whether he/she remains IC, I would think so unless they join a squad.
EDIT: What I should have stated here is that they retain an ICs special rules for dealing with incoming fire, unless they join a squad.
The rules for ICs on pg.51 of the main rulebook don't make mention of anyone's IC status being lost by buying a bike.
DE Faq. V.4.0.1
As to whether he/she remains IC, I would think so unless they join a squad.
EDIT: What I should have stated here is that they retain an ICs special rules for dealing with incoming fire, unless they join a squad.
The rules for ICs on pg.51 of the main rulebook don't make mention of anyone's IC status being lost by buying a bike.