Then again, 90% of the time someone writes "environment artist" they do mean prop artist. Its also often called world artist vs environment artist. People who do props are not often called "prop artists", its usually "environment artist" or just 3d-artist.
Environments are probably the best bet... they contain props too :) It shows a more broad skill-set (Lighting, composition, etc. ) plus I've seen more openings for Environment Artist rather than prop artist.
Yes it's ok, just give credit to the concept artist. In a production environment you'll often have to work off others' concepts. Depending on the situation you may have more freedom, and therefore would need some design skills.
What type of job? Do you want to be an Environment Artist, or do you want to be strictly a prop/asset artist? It would also help if we could see your current work, as Chris said. In general I think it's probably better to show you can do more than just props, but if your props are amazing, and you know you just want to do…
the last couple games I have worked on 70-80% of the assets were outsourced whereas the level artist team was about 15 people strong, placing, lighting, composing environments etc. I would focus on a couple really strong environment pieces that show: lighting, composition and texture knowledge.
Echoing the environment sentiment. You'll have lots of chances to make props, and also get the benefit of using those props in context as opposed to isolation. If you aren't sure which direction to go in, exploring environments should give you a good feel for making unique vs. modular assets so you can figure out what you…
Its a mixture, its important you can demonstrate what you intended to achieve. To help understand here is what I look for in a portfolio and why. Composition, Mood and Lighting - They can independently put a beautiful scene together. Technical Ability - They would be able to get straight to work without any help. Reference…