Taking the puppy out on leash to potty train is good advice. Not only will it allow you to confirm that the puppy has done her business, but you will also learn more about her "habits"--ie. when she needs to do what! You will also be aware if her habits/patterns change and if her stool changes. Knowing these types of information are basic ownership stuff, even if it's gross. If she's sick, you'll be surprised how anxious you'll be to see, even examine!, her stool!!
Aside from the above benefits, it is important for training, too. A leash will allow you to control where she goes. You can designate a special place in the yard for her "area". This makes cleaning the yard easier, and it keeps from "landmines" developing where you don't want them! Also, having a special place will help her go when you want her to. She'll associate the place with going to the bathroom, which will help her go.
Also, since you're on a leash and watching her closely, you'll be there to give a command to "go pottie" or "go poo". Associating a command with the action at this stage will allow you to make sure she goes when you leave for work or on a roadtrip.
Another training benefit is that you are right there at the end of the leash when she does go, so you can praise/treat her for going outside. The timing of praise/treat when house training is important; being there to praise her gently/quietly as she goes, and to then throw a party when she is done is VITAL to house training.
I've never used training pads inside. I use a crate during the house training phase, and dogs instinctively avoid going to the bathroom while in a kennel. However, at this stage, they can not be left long without getting to go outside. Any inside accident -- even those on pads while you aren't home-make it harder to housetrain. Crate training is necessary for this, so if you're interested, let me know!
As far as separation anxiety, you may find you have more difficulty than she does! Seriously, though, starting to leave in for short periods of time now is a good idea. Slowly increase those periods of time.
When you leave, do not make a big deal of it. Do not hug, kiss, say goodbye, I love you, I'll miss you etc. etc. The dog doesnt understand what you're saying; she'll just pick up on the saddness/anxiety emotions that you have as you do it. Instead, put her in her place (kennel, xpen, closed off area) without even talking to her. Leave without looking back as if leaving her is no big deal. If you dont think its a big deal, she'll learn its no big deal.
Same when you come home. Do not immediately go to her. Do something else when you get home before going to her. Use the bathroom, get a drink of water, tidy something up. Let her know that, just because you walked in the door, it isnt a big deal.
As you might suspect, it is emotionally difficult to ignore your baby, especially if she's crying out for you and all you want to do is love on her. It is important, though, to know this is part of the process of training a well adapted dog. It wont be difficult for ever, so it just takes a bit of reason and willpower to get through it.
Cedar (tri), Willow (blen), Holly (ruby), & Bella (blen)