As others have said, borrow books from the library, chat to other dog owners and chat to rescue centres, I've had 2 rescue dogs, my first was a 6yr old collie cross, she was house trained, very well behaved, but she wasn't great with other dogs, other than that she was great, very easy to care for. Slept in a dog bed downstairs, cried to go out at night if she had a bad tummy, otherwise slept through and didn't mess in the house at all.
My second rescue was much harder, he was a 1yr old stray, and needed house training, didn't like being left etc He was very hard work to train. But the rescue centres will be able to advise you.
My dogs have always come to work with me most of the time (I work part time as a Countryside Ranger) but if we get really hot weather (haven't had much the last couple of years) I leave them at home with access to the utility room and the garden, which they enjoy, but the garden is secure. The dog might be ok with a kennel, but it depends what its used to, and your garden would have to be fully secure.
They've always eaten a mix of dry and wet food. It depends on the size of dog and brand of food as to how much it costs.
I've got 2 dogs now, both from puppies, due to young dd, age 3. They probably cost about £15 per mth each to feed, £10-£20 per mth to insure, £60 vaccines annually, mine are covered for Kennel cough and routine vaccines, you'll also need to allow for worming and flea prevention treatment, toys, blankets, collar, tag lead, bed and what you do when you go on holiday.
Reptable rescue centres will have neutered, vaccinated and microchipped the dogs. Around here it costs about £100 for a dog, more for a puppy.
Our local rescue centre will let you register as a dog walker, where you can excercise and get to know dogs, you could also spot any great dogs that come in and snap it up, worth looking into with your local centres.