No. I would never get a piercing solely for someone else. Or at least not one I intended to keep. If I was more fond of tongue piercings, I might consider it. But I personally just don't really want one. There are plenty of other piercings I like more.
I have 3 already, but that's because I just love them. Nobody else wanted me to get them. I guess my equivalent would be would I take them out if a guy WASN'T interested? Well I might take them out when he was around, but mine are strange and will stay open for days on end. I wouldn't close them up just because someone else wanted me to.
No. I don't want to get my tongue pierced. End of story. I think tattoos can be pretty attractive on a guy, but I don't expect anyone to go out and get one for the sake of pleasing me. Some things just shouldn't be mandatory.