If a photographer takes photos for someone can they use those same photos for their own advertising?

It really depends on the contract terms and how you use the images to promote a photographic service. For example, if a photographer was commissioned to shoot "filler" or product shots for an internal publication (a manual, memo, quarterly report), for say Intel or Lockheed, they may have you sign a non-disclosure agreement because of the proprietary/ sensitive nature of their products. It may limit you on what you can do with your own images, but on the other hand, you can sell exclusive rights to the images for a higher fee. It all depends on the contract and how you negotiate your work. For your purposes, assuming the store owner agrees, you'd need a property release form; model releases are generally for people. And it also depends how the photographer is promoting their services - Portfolio? Print ad? etc.

Not without written permission from the primary individual shot in that picture. If it is a scenic type shot with no particular focus on the face of an individual - go for it!

It depends is the best answer... Technically, unless the copyright is specifically SOLD and CONTRACTED it belongs in all situations to the photographer. This means the photographer is normally fully entitled to use their own work, BUT... Things get more complicated if a model is involved, or if proprietary or sensitive commercial material is involved - in which case some kind of release form / contract will be required (if it isn't already in your standard Terms and Conditions of Service - it should be!). I would personally approach this by speaking to the client - it's good manners and may also save a legal or other mess. It could also jeopardise your ability to work for them again - and if you did a good job first time that would be a real shame as regular business is more valuable than a one-off job! (You do not have to advertise for them or to meet them and make a sales pitch for example.) Normally the client will be only too happy to let you use them in my experience, especially if they are offered some reciprocal PR such as a link back to their website, a tag line stating the clients name, etc. This also gives you some 'brand association' and the option of asking them for a link back too, which benefits both of you in terms of site traffic and search engine optimisation. The situation is different in reverse though - the client can only use your images for the specific purpose(s) for which they were commissioned. Change of purpose (taking the PR shots and making a calendar for example) would mean the photographer would be entitled to charge a second, and sometimes much more significant fee.

You should be able to. If you are a serious photographer then you should have your clients sign a standard release form saying that the person allows you to use the pictures in various ways. This is more necessary when you have models, but it's always good to have your clients sing a form. However, since it is your photography then it's your right to use it on display for your own advertisement, and because it's just a store, you should be fine.

it depends, if someone used the picture someone else already either owns or has rights on it could be considered copyright, which is illegal. The person would most likely have to talk to a store owner or manager, and even possibly the photographer. Hope I helped.

As a photographer, you should have your clients sign a model release form -- this gives you the rights to use any photo you take for advertising. If they aren't willing to sign it, you just have to respect that and you can't use the pictures. Most people will sign it though.

Sorry but if it was a commission then the copy right belongs to the store so they would have to give permission for you to use them. Unless you have an agreement before hand.