Got a character who wants to have a "pet" in one of my campaigns to help with tracking- problem is that the pet (dog) would have to follow them around etc, and the character is not a ranger- how would I go about the "payment" of basically an animal companion when the character's class is not one that has the companion class feature? Is it just a feat to get one or what? (This is in 3.5)

Actually, this one is easily figured. The PHB has prices for a Riding Dog. Using the Handle Animal skill, you teach it the "Track" trick. After that, it's just care of the dog.

And it's not at all like an animal companion considering it doesn't scale. A dog will remain a dog at all levels, after all. Buy the thing and tend to it.

That's the question I had in mind- how to keep the dog alive if it is going to be put in dangerous situations? To allow it to have extra hit die? Because as it stands it might have 2 HD when the party reaches level 7. I guess more specifically- how much would it cost for a class that doesn't have the animal companion feature, get the feature?

Just keep the dog out of the line of fire. No need to worry there. If it dies, buy a new dog and watch that one better.

However, if you absolutely need it to be an animal companion, then just make it a feat.

I'd say buy a dog and train it as described above. If the PC wants the dog to become something more, then at level six, have him invest a feat in Leadership and make the dog his cohort.

Wild Cohort feat. Also, start with a Magebred Warbeast or something.

In order to maintain concentration on spell do you need to keep LoS and/or LoE to the target / affected area?

3.x or 4e?

In 4e the spell needs to be within range of the power's description, and can break LoS or LoE

Sorry: D&D 3.5.