Their defence was garbage last year too. I don't think its due to personnel (apart from Kepa, but Pickford is also shite for Everton and they have a better defence). Its down to whatever tactics lampard has them playing. Makes for exciting football, but definitely not something that will win the bigger things.
As for the rest, yeah they spent a lot but a lot of them are still young, itll take some adaptation time. I'm sure they'll get top 4 in the end, but they won't run away with it over the other competitors.