Hi there

Hope i can help as i'm hoping to be starting a course in canine behaviour and dog training.

I have introduced clicker training to both my dogs and had fabulous results although it does take longer with the bassett hound than it does the Collie cross but it does work in the end some breeds do take longer for the penny to drop. My collie X house trained in one day. I troduced the clicker right from the start so he understood that click meant reward i also made a point of leaving the door open all the time until i knew he had it. Okay in the summer not so good this time of year the moment he started doing his business in the garden i clicked the behaviour he then returned to me for over the top praise and treat.

As far as letting you know when they want to go out this seems to be dependant on the dog Trip tends to hover around the door until you notice he's not vocal. my parents Shi tzu used to sit and whine in front of you. you then went through a list - sweeties, play, walkies weeweeies - and she would bark when you got to the one she wanted.
You can train dogs to give a clear signal similar to the ways hearing dogs for the deaf alert their handlers or the dog will develope its own way once he's learnt theres only one place to do it.

For loads of advise on clicker training from beginners to expert look up the following website
Learning About Dogs - Welcome

Let me know how yopu get on feedback would be appreciated