I'm sure that can be used in a shower, but what most will probably tell you is that smaller tiles such as those will look very busy. The larger the tile, the larger it will make your space look. Small glass mosaic tiles also tend to be very pricey which is why often times, they're used as accent pieces. In the very beginning stages of our remodel, I found it helpful to look through the books at Lowes and Borders to see what styles would work best and what materials were used and it was very helpful.

The trend lately has been to use large format tiles on the bathroom floor, so people will usually pick a smaller coordinating tile for the shower, so you might have gotten used to that look. Plenty of people do the smaller tiles throughout too. It looks nice and well done. I'm remodeling and picked a really large tile for the bathroom floor and in the shower I went with the same tile and color, but in a 2" x 2" size.

I've never seen any tile come with instructions. I did my first DIY tiling project ever earlier this year. I completely tiled my floor and bath tub / shower surround in a medium sized main bathroom. I am extremely pleased with the result. However, I won't lie to you. It was hard, frustrating, exhausting, and rewarding. It took a LONG time (months) to do it by myself. (My father periodically came over to assist with tile cutting, but otherwise it was all me. My significant other was deployed for some military training.) My suggestion would be to read. And then read more. Read threads on this forum. Then go to your local library (or book store) and look up books on tiling. This book from my local library was particularly helpful for me. There are some really important things you must not neglect. 1. Build your substrate correctly. You need waterproofing and you need to make certain the material you're tiling is appropriate for tile and wet areas. 2. Plan your layout. Draw it out. Most tiling books discuss layouts and you can always ask questions here. A good layout is crucial to having a nice result. 3. Use the proper thinset. There are instructions in books and on this forum on when to use what thinset. If you were working with a tile store, they would be able to assist with this as well. 4. Use tiles appropriately. Use the right type of tile for the right type of application (floor, wall, etc). Make certain to follow manufacturer guidelines on grout spacing, etc. It is definitely possible to DIY tile a shower. It will take time and be frustrating, but you can get through it. It will save a bunch of money IF you do it right. You do not want to rush through something, do it wrong, and then have to pay someone to come fix it in the future.

No rules. Its an aesthetic that may also be dictated by the size of the tile and possible miters. If you need layout help you need to share photos.