Yes, the tape strip is from the flap of the cel 
bag that's folded underneath.  The part with the 
lettering on it can be peeled off to seal the 
bag, but most dealers leave it on because 
collectors like to take the cels out for 
inspection and scanning, and the adhesive is 
really really sticky.  (I've come close to 
creasing a cel by tugging and pulling the flap of 
a sealed cel bag open.)  I think the lettering is 
the brand name of the cel bag written over and 
over.

I'm not a Cowboy Bebop collector, but the cels 
look real to me.  They have sequence numbers and 
an annotated douga, which most fancels 
conspicuously lack.  Obviously, though, you'd 
want to get an opinion from someone who knows 
what this studio's cels/dougas look like before 
taking my word for it.