Hi Ruben, welcome to the forum and nice looking kit you scored.
as others have said choose the bridge carefully so I wouldn't go over 17mm string spacings or the B and G strings will be too close to the edge of the fingerboard.
See the Ibanez pictured has the 3 tuning pegs on the treble side of the headstock (PBG has 3 on the bass side)
For staining rag try get some lint free cloth, otherwise if the t-shirt is pretty fine grade it will be fine for staining.