
Karen - I would forget the paper training and use the garden immediately. If you paper train indoors, you are only teaching the pup that it is OK to go indoors and then when you want it to perform outside this can be a little confusing for him/her ;)
I have trained all of my dogs outside in my garden from day one without any health problems whatsoever.
I don't think you are being cautious or overprotective re the Lab, just using common sense. you don't want that first experience with another dog to be a traumatic one for her. This could cause issues with her when teaching her doggy etiquette later on. :D I've had a dog that was "set upon" in rough play when she was young and it took her a good while to learn to trust her own species after that.
Puppy classes are a great idea. Remember to go to a few without your pup first of all so that you are comfortable, know what to expect, like the training methods, etc :)
Oh, finally, good luck, bet you can't wait :)
Edited to say: posting the same time as Roz :)