3M VHB Tape RP32 2 in Width x 5 yd Length (1 Roll)

Q: whats the thickness of this tape ?

Product Specifications: 0.032 in. thick, 2 in. wide, and 15 ft. long

Q: Is the tape removable if you want to change installation or replace tape?

You can remove it, though it is a pain to do so. Depending on what you're taping/how much tape you are using, I have found that running dental floss or a thin steel wire between the two surfaces helps to cut the tape and separate the surfaces, then you need to remove it from each surface.