The porosity of the tiles doesn't matter - the waterproofing happens on the layer below. You'll want to use something like Kerdi (the Kerdi shower pan kit is nice) or a similar product, or RedGuard, or another form of waterproofing.
The problem with marble is that it's a limestone type of stone, and susceptible to chemical attack. Over time it will lose it's gloss and go dull. How long this takes will depend greatly on your water and the products you use. It might only last a few years or it might outlast you. When it dulls you can either polish or replace.
JohnBridge.com is a tile forum, and the topic of marble showers has been discussed there. You might get some good info by browsing old topics. And John Bridge himself has a marble floor in his shower and wrote an article about it. He lists a recommended sealer and has some brief instructions on using it, too.
Answer from Sean on Stack ExchangeVideos
What are the benefits of using marble tiles in a shower?
What types of marble are best for shower wall tiles?
How can I prevent my marble shower tiles from staining?
The porosity of the tiles doesn't matter - the waterproofing happens on the layer below. You'll want to use something like Kerdi (the Kerdi shower pan kit is nice) or a similar product, or RedGuard, or another form of waterproofing.
The problem with marble is that it's a limestone type of stone, and susceptible to chemical attack. Over time it will lose it's gloss and go dull. How long this takes will depend greatly on your water and the products you use. It might only last a few years or it might outlast you. When it dulls you can either polish or replace.
JohnBridge.com is a tile forum, and the topic of marble showers has been discussed there. You might get some good info by browsing old topics. And John Bridge himself has a marble floor in his shower and wrote an article about it. He lists a recommended sealer and has some brief instructions on using it, too.
No you can't. My first thought on looking at this is that it isn't rated for flooring (marble breaks pretty easy if thinly cut).
And then looking at Lowe's specifications here it is not rated for any flooring use, including bathrooms.