What is your opinion of these careers (stripping, porn, prostitution, escorting, etc.)?
I can't add to what MR3 said...it's merely the marketing of a skill that a person realizes that they have. And no question, it is very much a skill (and not all bodies and physiques are equally "qualified" for it).
For those of you who had the body and the confidence, would you do it?
No, it requires far more sexual diversity and flexibility than I've ever had. Being able to be aroused with a partner who may do absolutely nothing for you at all, is a skill that not all people have, but it's an important one and a lot of guys also "get off on" satisfying the other person. That feeling doesn't change if the other person is an escort/prostitute.
OK, just realized I was answering only half the question. If I had the body and the confidence, stripping would be the "easiest" of the alternatives. Porn would be more difficult than escort/prostitution in some ways, and easier in other ways. Porn usually requires a massive repertoire of sexual likes and turn-ons if the resulting porn is to be believable, but an escort can ask a customer ahead of time to be specific about what they want. (In these professions which involve sex with partners, the professional has the option not to include some practices that they may not like - usually the more exotic kink such as scat, extreme BDSM, fisting, etc.) Being a stripper is the only one of these I could have ever imagined doing myself, because my sexual tastes have always been excessively vanilla, and that can be extremely limiting within the profession. On the other hand, porn OFTEN/USUALLY involves partners which one is *likely* to find attractive and usually limited to a fairly narrow age and weight range, while with paid non-porn sex the physical attributes are a complete roll of the dice. In fact, with escorts/prostitutes, the partners are rather more likely NOT to be that physically "beautiful" because it's much rarer for the "gorgeous" guys to go out and pay for what they can easily get free.
More importantly, could you date and/or get seriously involved with someone who's been in, or is currently in, that industry?
I'm not even sure - it's one of those "cross that bridge when I get to it" types of questions. My first inclination is "no" but that's not a guaranteed answer. I'm maintaining an ordinary platonic friendship with an escort who I originally hired a few years ago.