How long is a full feed - it's not usually a "time" per say, but until the baby is satisfied. When you're finished the BF session, your baby should look content and very sleepy for the first few weeks, but then usually fairly alert and interested in you for a short time, once she's older. For an efficient eater, if could be about 15 min at that age for a full feed, but if she's not an efficient eater, then it could be closer to 45 min. Usually, when a baby is not very "efficient", it's due to a poor latch or something like a tongue tie - did the LC say anything about that? BTW, do you have any sore SPOTS on your nipple -like there's a spot that keeps rubbing? Any scabs or bleeding? Your nipple should not look deformed at all when it comes out of her mouth, but should stay pretty symmetrical.
As for your question 2, I'm not sure what you mean.... Yes, you can cluster feed when just BF'ing, particularly in the evening when naps are a bit shorter - it really depends how long your lo is sleeping. For longer EASY cycles, you nurse when she wakes and also right before a nap, but not nursing to sleep. The other way is to nurse, then as soon as your lo goes down for a nap, pump.
Yes, it's better not to use the soother, and bottles can be risky. Make sure to use a very very slow flow nipple on the bottle so the baby doesn't prefer the fast flow vs your breast.
I personally always liked double sided feeding, but regardless, breast compression can be really really helpful when she starts to slow down - it can make you more confident that she's really done.